JP7226006B2 - Organic silica substrate for laser desorption/ionization mass spectrometry and laser desorption/ionization mass spectrometry using the same - Google Patents

Description

The present invention relates to an organic silica substrate for laser desorption/ionization mass spectrometry and laser desorption/ionization mass spectrometry using the same.

Mass spectrometry (MS) ionizes a sample containing a molecule to be measured, and separates and detects ions derived from the molecule to be measured according to the mass-to-charge ratio (mass/charge (m/z)). This is an analysis method for obtaining information on the chemical structure of the molecule to be measured. In such mass spectrometry (MS), the ionization of a sample is an important process that determines whether analysis is possible and the quality of the spectrum obtained. (laser desorption/ionization: LDI) is known. In recent years, in mass spectrometry employing such laser desorption/ionization (LDI), various types of substrates for analysis have been studied in order to further improve the accuracy of the analysis. .

For example, in Japanese Unexamined Patent Application Publication No. 2014-115187 (Patent Document 1), an organic silica porous material having an organic group capable of absorbing laser light as a skeleton is used as a substrate (organic silica substrate) for laser desorption/ionization mass spectrometry. disclosed to use. Further, in JP 2018-185200 A (Patent Document 2), it has an organic group capable of absorbing laser light in its skeleton, has pores with an average pore diameter of 5 to 50 nm, and has a surface aperture ratio disclosed is an organosilica substrate for laser desorption/ionization mass spectrometry, comprising an organosilica porous membrane having a λ of 33-70%. Such organic silica substrates for laser desorption/ionization mass spectrometry as described in Patent Documents 1 and 2 do not use a matrix compound during mass spectrometry when used for laser desorption/ionization mass spectrometry. Even so, it was possible to detect the signal of the molecule to be measured with sufficient sensitivity. However, even organic silica substrates such as those described in Patent Documents 1 and 2 are not necessarily sufficient in terms of performing mass spectrometry with high reproducibility at a plurality of measurement points in the region to which molecules to be measured are attached. It was nothing.

JP 2014-115187 A Japanese Patent Application Laid-Open No. 2018-185200

The present invention has been made in view of the above-mentioned problems of the prior art, and makes it possible to detect the signal of a molecule to be measured with sufficiently high sensitivity without using a matrix compound during mass spectrometry, When mass spectrometry is performed on a plurality of measurement points in the region to which the sample containing the molecule to be measured is attached, the uniformity of the signal intensity of the mass spectrum obtained can be increased, and each measurement An object of the present invention is to provide an organic silica substrate for laser desorption/ionization mass spectrometry that enables mass spectrometry with higher reproducibility at a point, and a laser desorption/ionization mass spectrometry method using the same. do.

As a result of intensive studies to achieve the above object, the present inventors have found that an organic silica substrate for laser desorption/ionization mass spectrometry is an organic silica substrate having an organic group capable of absorbing laser light in its skeleton. A silica thin film is provided, the organic group capable of absorbing laser light has a maximum absorption wavelength in a wavelength range of 200 to 1200 nm, and the organic silica thin film extends from the surface of the organic silica thin film in the depth direction. By containing 0.5 to 4.0 at% of titanium oxide in the region up to 10 nm in terms of titanium element ratio, the signal of the molecule to be measured can be obtained without using a matrix compound during mass spectrometry. can be detected with sufficiently high sensitivity, and the signal intensity of the mass spectrum obtained when mass spectrometry is performed on multiple measurement points in the region where the sample containing the molecule to be measured is attached The inventors have found that it is possible to increase the uniformity of , and it is possible to perform mass spectrometry with higher reproducibility at each measurement point, and have completed the present invention.

That is, the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention comprises an organic silica thin film made of organic silica having an organic group capable of absorbing laser light in its skeleton, and the organic group capable of absorbing laser light is has a maximum absorption wavelength in the wavelength range of 200 to 1200 nm, and titanium oxide has a titanium element ratio of 1.0 to 2.0 nm within a range of 10 nm in the depth direction from the surface of the organic silica thin film. It is characterized by containing 0 at % .

In the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention, the organic group capable of absorbing laser light preferably has a maximum absorption wavelength in the wavelength range of 200 to 600 nm.

In the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention, the organic silica thin film preferably has an uneven structure with a roughness factor of 1.4 or more on its surface.

Furthermore, in the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention, the organic silica thin film preferably has a hydrophobic group on its surface.

Further, in the laser desorption/ionization mass spectrometry of the present invention, the substrate for analysis used in the laser desorption/ionization mass spectrometry is the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention. It is a method characterized by

The reason why the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention achieves the above object is not necessarily clear, but the present inventors speculate as follows. That is, first, the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention (hereinafter sometimes simply referred to as the “organic silica substrate of the present invention”) has a maximum absorption wavelength in the range of 200 to 1200 nm. and a thin film made of organic silica having a skeleton of an organic group capable of absorbing laser light. When such an organic silica thin film is irradiated with laser light, the laser light is absorbed by the organic groups in the thin film, and the energy of the laser light absorbed by the thin film is placed (carried) on the substrate. It is possible to efficiently move the molecule to be measured, thereby enabling desorption/ionization of the molecule to be measured (such performance is hereinafter sometimes referred to as "LDI support performance"). In other words, in the organic silica substrate of the present invention, the organic group in the organic silica thin film absorbs the laser light irradiated during mass spectrometry, and the energy generated accompanying the absorption of the laser light (for example, the absorption of the laser light The organic group is photoexcited by the photoexcitation, and the accompanying thermal energy, etc.) can be transferred to the molecule to be measured (substance to be analyzed) supported on the surface of the organic silica thin film, so it is efficient Energy transfer can be performed, which enables efficient desorption/ionization of molecules to be measured (analytes). Due to such LDI-assisting performance, the organic silica substrate of the present invention can utilize the energy of the laser light more efficiently. It is presumed that it is possible to more efficiently desorb/ionize the molecule to be measured without using a matrix compound (low-molecular-weight additive) used in assisted laser desorption/ionization (MALDI).

Further, in the present invention, the organic silica thin film contains 0.5 to 4.0 atomic % of titanium oxide in terms of titanium element ratio in a region within a range of 10 nm in the depth direction from the surface of the organic silica thin film. It is a thing. Such titanium oxide has polarity and interacts with the polar functional group of the substance to be analyzed. functions as an adsorption point (adsorption site) of Since titanium oxide is present on the surface of the organic silica substrate of the present invention at a specific concentration (0.5 to 4.0 at % in terms of titanium element ratio), the surface of the organic silica substrate has Adsorption points are uniformly present. Therefore, it is presumed that the organic silica substrate of the present invention can support the molecules to be measured more uniformly than when the molecules to be measured are supported in the absence of titanium oxide. .

Here, a case where a conventional organic silica thin film containing no titanium oxide on the surface is used as an organic silica substrate will be discussed below with reference to FIG. That is, first, when a sample solution 11 containing molecules to be measured is applied to the surface of a conventional organic silica thin film 10 (FIG. 1(a)), the solvent contained in the solution 11 evaporates. The sample S is gradually supported (FIG. 1(b)), and when the solvent is finally completely removed (evaporated), all of the sample S contained in the solution 11 is removed from the organic silica thin film 10. supported on the surface. Thus, the sample S is supported on the surface of the organic silica thin film 10 as the solvent is removed from the solution 11 . However, since the surface of the conventional organic silica thin film 10 does not necessarily have a uniform site that allows adsorption of the sample S containing the molecule to be measured (analyte), the organic silica substrate of the present invention is not uniform. As a result, the sample S cannot necessarily be carried uniformly, and in the region where the solution 11 is applied, there is a region V in which the amount of the sample S carried (attached amount) is small or the sample S is not carried. It is thought that it becomes easy to occur.

In contrast, the organic silica substrate of the present invention has titanium oxide present on its surface at a specific concentration (0.5 to 4.0 at % in terms of titanium element ratio), and the titanium oxide adsorbs the sample. Since it has an effect, based on the adsorption effect, when the solution is applied on the substrate, the adsorption of the sample contained in the solution (attachment of the sample to the substrate) is made more uniform. Based on such adsorption of the sample, when mass spectrometry is performed on a plurality of measurement points in the region where the molecule to be measured is attached, the uniformity of the signal intensity of the mass spectrum obtained is higher. As a result, the present inventors speculate that mass spectrometry with higher reproducibility can be performed at each measurement point. As described above, in the organic silica substrate of the present invention, the titanium oxide, which is the adsorption site for the substance to be analyzed, is introduced onto the surface of the organic silica thin film in the above ratio, so that the molecules to be measured ( It is possible to make the support (attachment) of the sample containing the molecule to be analyzed highly uniform, and to measure multiple points within the analysis area (the area where the sample containing the molecule to be measured is attached) on the organic silica substrate. , the signal of the molecule to be measured (analyte) can be detected with the same intensity at any measurement point, and the molecule to be measured (analyte) can be detected with good reproducibility regardless of the position of the measurement point. The present inventors presume that it is possible to detect the signal of the target substance).

According to the present invention, it is possible to detect the signal of the molecule to be measured with sufficiently high sensitivity without using a matrix compound during mass spectrometry. When mass spectrometry is performed at multiple measurement points, the uniformity of the signal intensity of the mass spectrum obtained can be made higher, and mass spectrometry with higher reproducibility can be performed at each measurement point. It is possible to provide an organic silica substrate for laser desorption/ionization mass spectrometry and a laser desorption/ionization mass spectrometry using the same.

FIG. 2 is a schematic diagram showing an embodiment in which a conventional organic silica thin film is coated with a sample solution. 1 is a schematic longitudinal sectional view schematically showing a preferred embodiment of a laminate including an organic silica thin film (porous film); FIG. 3 is an enlarged view of a region R of the organic silica thin film shown in FIG. 2; FIG. 1 is a graph showing ultraviolet/visible absorption spectra of an organic silica thin film (measurement sample) obtained using a compound represented by formula (A) below. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 2 (mass spectrometry using the organic silica substrate obtained in Example 1). is. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 2 (mass spectrometry using the organic silica substrate obtained in Example 1). is. As a result of the mass spectrometry performed in Example 2 (mass spectrometry using the organic silica substrate obtained in Example 1), the signal intensity of the mass spectrum (LDI-MS spectrum) at each measurement point was measured at 10 points. It is a graph shown for each. As a result of the mass spectrometry performed in Comparative Example 2 (mass spectrometry using the organic silica substrate obtained in Comparative Example 1 ), the signal intensity of the mass spectrum (LDI-MS spectrum) at each measurement point was measured at 10 points. It is a graph shown for each. As a result of the mass spectrometry performed in Comparative Example 5 (mass spectrometry using the organic silica substrate obtained in Comparative Example 3 ), the signal intensity of the mass spectrum (LDI-MS spectrum) at each measurement point was measured at 10 points. It is a graph shown for each. As a result of the mass spectrometry performed in Comparative Example 6 (mass spectrometry using the organic silica substrate obtained in Comparative Example 4 ), the signal intensity of the mass spectrum (LDI-MS spectrum) at each measurement point was measured at 10 points. It is a graph shown for each. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 4 (mass spectrometry using the organic silica substrate obtained in Example 3 ). is. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 4 (mass spectrometry using the organic silica substrate obtained in Example 3 ). is. As a result of the mass spectrometry performed in Example 4 (mass spectrometry using the organic silica substrate obtained in Example 3 ), the signal intensity of the mass spectrum (LDI-MS spectrum) at each measurement point was measured at 10 points. It is a graph shown for each. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 5 (mass spectrometry using the organic silica substrate obtained in Example 3 ). is. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 6 (mass spectrometry using the organic silica substrate obtained in Example 3 ). is. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 6 (mass spectrometry using the organic silica substrate obtained in Example 3 ). is. 4 is a scanning electron microscope (SEM) photograph of the surface of the organic silica thin film prepared in Example 7. FIG. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 8 (mass spectrometry using the organic silica substrate obtained in Example 7 ). is. A graph of a mass spectrum (LDI-MS spectrum) obtained at an arbitrary measurement point as a result of the mass spectrometry performed in Example 8 (mass spectrometry using the organic silica substrate obtained in Example 7 ). is.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to its preferred embodiments.

[Organic silica substrate for laser desorption/ionization mass spectrometry]
The organic silica substrate for laser desorption/ionization mass spectrometry of the present invention comprises an organic silica thin film made of organic silica having an organic group capable of absorbing laser light in its skeleton, and the organic group capable of absorbing laser light has a wavelength of It has a maximum absorption wavelength in the range of 200 to 1200 nm, and titanium oxide is 0.5 to 4.0 at% in terms of titanium element in a region of 10 nm in the depth direction from the surface of the organic silica thin film. It is characterized by containing

The organic silica thin film according to the present invention is a thin film made of organic silica having an organic group capable of absorbing laser light in its skeleton.

Thus, the organic silica constituting the thin film has an organic group capable of absorbing laser light in its skeleton. Such an “organic group capable of absorbing laser light” is an organic group having a maximum absorption wavelength in the wavelength range of 200 to 1200 nm (more preferably 200 to 600 nm, still more preferably 250 to 450 nm, particularly preferably 300 to 400 nm). is the base. If the absorption maximum wavelength of such an organic group is less than the lower limit, when laser desorption/ionization (LDI) is used, when laser light with such a wavelength is absorbed, the object to be measured (molecule to be measured) At the same time, the organic groups in the organic silica thin film are decomposed by the light, and as a result, efficient mass spectrometry tends to be difficult. , it tends to be difficult to obtain the light energy necessary for ionizing the molecule to be measured. In this way, the organic group having a maximum absorption wavelength in the above wavelength range makes it possible to more efficiently absorb laser light in the wavelength range used for mass spectrometry.

Further, examples of the "organic group capable of absorbing laser light" that the organic silica thin film has in the skeleton include an organic group having a structural portion capable of absorbing laser light used in mass spectrometry. be done. As such an organic group, depending on the wavelength of the laser light to be used, an organic group having an aromatic ring as a structural portion capable of absorbing laser light (e.g., triphenylamine, naphthalimide, fluorene, acridone , methylacridone, quaterphenyl, anthracene, etc.). As described above, the organic group capable of absorbing laser light (an organic group having a maximum absorption wavelength in the wavelength range of 200 to 600 nm) includes, for example, triphenylamine, na phthalimide, styrylbenzene, fluorene, divinylbenzene, divinylpyridine, acridone, methylacridone, quaterphenyl, anthracene and the like.

Furthermore, such an organic group capable of absorbing laser light (preferably an organic group having a maximum absorption wavelength in the wavelength range of 200 to 600 nm) is more preferably an aromatic organic group containing 10 or more carbon atoms. preferable. Such an aromatic organic group enables more efficient absorption of laser light. Examples of such aromatic organic groups include, for example, triphenylamine, naphthalimide, styrylbenzene, fluorene, acridone, methylacridone, quaterphenyl, anthracene, pyrene, acridine, each of which may have a substituent. , phenylpyridine, perylene, perylenebisimide, diphenylpyrene, tetraphenylpyrene, porphyrin, phthalocyanine, diketopyrrolopyrrole, dithienylbenzothiadiazole and the like. Further, the organic silica thin film may have one type of organic group alone as an organic group, or may have a combination of a plurality of types of organic groups. Among such organic groups, from the viewpoint of chemical stability against light irradiation, at least one of triphenylamine, naphthalimide, pyrene, perylene, and acridone (at least one of the organic groups is at least one of triphenylamine, naphthalimide, pyrene, perylene and acridone).

In addition, in the organic silica thin film, “having an organic group in its skeleton” means that the organic means that a group is present. Such an organic silica thin film has a structure (crosslinked structure) in which silicon atoms forming a siloxane structure (formula: -(Si-O) _y -structure) are crosslinked by an organic group. It is more preferable that an organic group is introduced into.

In the organic silica thin film, the content ratio of silicon constituting the organic silica and the organic group capable of absorbing laser light is the ratio of the mass of silicon to the mass of the organic group ([mass of silicon]/[organic Group mass]) based on the A range is preferred. When such a mass ratio ([mass of silicon]/[mass of organic group]) is less than the above lower limit, the crosslink density of the organic silica thin film tends to be low and the film tends not to be sufficiently cured. When the density of the organic group is relatively decreased, the absorption intensity of the laser beam tends to be decreased. At some stage, the degree of cross-linking tends to increase excessively, making it difficult to form an uneven structure by nanoimprinting. The organic silica thin film having such a mass ratio has an organic group having a maximum absorption wavelength in the wavelength range of 200 to 600 nm as an organic group capable of absorbing laser light, and the content ratio of silicon and the organic group is 0.05 to 0.50 (more preferably 0.10 to 0.40, more preferably 0 0.10 to 0.35, particularly preferably 0.15 to 0.35).

Examples of such organosilicon compounds include the following general formulas (1-i) to (1-iv):

[In the formulas (1-i) to (1-iv), X represents an m-valent organic group, R ¹ represents an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), a hydroxyl group (-OH), , an allyl group (CH ₂ ═CH—CH ₂ —), an ester group (preferably an ester group having 1 to 5 carbon atoms) and a halogen atom (chlorine atom, fluorine atom, bromine atom, iodine atom). R ² represents at least one selected from the group consisting of an alkyl group and a hydrogen atom, and n and (3-n) are each bonded to a silicon atom (Si) R ¹ and R ² , n is an integer of 1 to 3, m is an integer of 1 to 4, L in formula (1-iv) is a single bond or an ether group, an ester group, an amino group, represents any one divalent organic group selected from the group consisting of an amide group and a urethane group, and Y in formula (1-iv) represents an alkylene group having 1 to 4 carbon atoms. ]
and the content ratio of silicon and the organic group capable of absorbing light is the ratio of the mass of silicon to the mass of the organic group capable of absorbing laser light ([mass of silicon] / [mass of organic group]) Organosilicon compounds in the range of 0.05 to 0.50 on the basis of are preferred. Regarding the "organic group capable of absorbing laser light" in the compounds represented by the general formulas (1-i) to (1-iv), the compounds represented by the general formula (1-i) In the formula, the group represented by X (m-valent organic group (bonds are omitted)) is an “organic group capable of absorbing laser light” and is represented by the general formula (1-ii) In compounds, the formula:

[In formula (I), X represents an m-valent organic group, and m represents an integer of 1 to 4 (thus, X and m are represented by general formulas (1-i) to (1-iv) are synonymous with X and m in ). ]
The organic group represented by is an "organic group capable of absorbing laser light", and in the compound represented by the general formula (1-iii), the formula:

[In formula (II), X represents an m-valent organic group, and m represents an integer of 1 to 4 (thus, X and m are represented by general formulas (1-i) to (1-iv) are synonymous with X and m in ). ]
The organic group represented by is an "organic group capable of absorbing laser light", and in the compound represented by the general formula (1-iv), the formula:
X—(L—Y) _m − (III)
[In the formula (III), X represents an m-valent organic group, L is a single bond or any one divalent selected from the group consisting of an ether group, an ester group, an amino group, an amide group and a urethane group represents an organic group, Y represents an alkylene group having 1 to 4 carbon atoms, m represents an integer of 1 to 4 (thus, X, L, Y and m are in the general formula (1-iv) are synonymous with X, L, Y and m of ). ]
The organic group represented by is the "organic group capable of absorbing laser light". Thus, the organic group of the structural portion containing the group represented by X in the formula, which is a group that bonds to silicon in the compound, is an "organic group capable of absorbing laser light".

The organic silica thin film is represented by the above general formulas (1-i) to (1-iv), and the content ratio of silicon and the organic group capable of absorbing light is equal to that of the organic group capable of absorbing light. A group consisting of organosilicon compounds in the range of 0.05 to 0.50 based on the ratio of the mass of silicon to the mass ([mass of silicon]/[mass of organic group]) (hereinafter referred to as For convenience, the group is sometimes simply referred to as "compound group (A)"). Thus, the organic silica thin film is preferably an organic silica thin film made of a polymer of one type of organic silicon compound selected from the compound group (A).

According to the organic silica thin film composed of a polymer of at least one organic silicon compound selected from the compound group (A), the so-called light-collecting antenna function tends to be exhibited more efficiently. , which tends to make it possible to ionize molecules to be measured more efficiently. The term "light collection antenna function" used herein refers to the function of absorbing light energy when irradiated with light and concentrating the excited energy inside the pores. It tends to be possible to efficiently move the light energy of the laser beam that has been applied to the molecule to be measured carried inside the pores. The definition of such a "light collection antenna function" is the same as the definition described in Japanese Patent Application Laid-Open No. 2008-084836.

In addition, the polymer of at least one organosilicon compound selected from the compound group (A) forms a siloxane structure (structure represented by the formula: -(Si-O) _y -). It has a structure (crosslinked structure) in which silicon atoms are crosslinked by organic groups, and thereby has a structure having the above-mentioned organic groups in the skeleton (so-called "crosslinked organic silica thin film"). Here, taking as an example the polymerization reaction of an organosilicon compound represented by the general formula (1-i) in which R ¹ is an ethoxy group, n is 3, and m is 2, such a crosslinked structure will be explained. The following general formula (2):

[In the formula, X represents an m-valent organic group, and p represents an integer corresponding to the number of repeating units. ]
In the organic silica thin film obtained after polymerization, the silicon atoms forming a siloxane structure (structure represented by the formula: -(Si-O) _y -) with the organic group (X) are crosslinked. (Although the number of p is not particularly limited, it is generally preferably in the range of about 10 to 1000.). In addition, when such a crosslinked structure is formed (when the organic silica thin film becomes the crosslinked organic silica thin film), when this is used for mass spectrometry, the irradiated laser light is absorbed more efficiently, and the organic There is a tendency that the excitation energy can be transferred more efficiently to the molecule to be measured supported in the pores of the silica thin film. In addition, the organic silica composed of a polymer having a repeating unit represented by the general formula (2) has a ratio of the total amount (mass) of the organic group (X) to the total amount (mass) of Si in the organic silica [mass of silicon]/[mass of organic group]) is preferably in the range of 0.05 to 0.50.

Further, as R ¹ in the general formulas (1-i) to (1-iv), an alkoxy group and/or a hydroxyl group are preferable from the viewpoint of easy control of the condensation reaction (polymerization reaction). In addition, when a plurality of R ¹ are present in the same molecule, the R ¹ may be the same or different. An alkyl group having 1 to 5 carbon atoms is preferable as the alkyl group that can be selected as R ² in general formulas (1-i) to (1-iv). In addition, when multiple R ² are present in the same molecule, the R ² may be the same or different.

In general formulas (1-i) to (1-iv) above, n and (3-n) indicate the numbers of R ¹ and R ² bonded to silicon atoms (Si), respectively. Here, n represents an integer of 1 to 3, and n is particularly preferably 3 from the viewpoint that the structure after condensation can be made more stable.

Furthermore, m in the above general formulas (1-i) to (1-iv) represents the number of silicon atoms (Si) directly or indirectly bonded to the organic group (X). Such m represents an integer of 1-4. Such m is more preferably 2 to 4 (particularly preferably 2 to 3) from the viewpoint of easy formation of a stable siloxane network.

Further, from the viewpoint of ensuring high chemical stability, L in formula (1-iv) is more preferably a single bond or an ether group. When multiple L's are present in the same molecule, the L's may be the same or different. Furthermore, Y in formula (1-iv) is more preferably an ethylene group or a propylene group from the viewpoint of achieving both high density of silicon after polymerization and flexibility of the film. When multiple Y's are present in the same molecule, Y's may be the same or different.

Further, X in the general formulas (1-i) to (1-iv) represents an m-valent organic group. In addition, among such m-valent organic groups, the following general formulas (101) to (112):

[In the above general formulas (101) to (112), the symbol * indicates that the bond with the symbol is a bond that bonds to X in the above formulas (1-i) to (1-iv). show. ]
An organic group represented by is particularly preferred. In the organic groups represented by the general formulas (101) to (112), the bond represented by the symbol * is directly bonded to silicon from the viewpoint of increasing the density of the organic group and stably immobilizing it. more preferably.

Furthermore, as the "organic group capable of absorbing laser light" possessed by the organic silica thin film, from the viewpoint of the ability to absorb laser light with a wavelength of 300 to 400 nm and high chemical stability, an organic group containing a naphthalimide ring in the structure is preferred, and any one of the organic groups represented by the general formulas (102) to (103) (organic groups containing a naphthalimide ring in the structure) is particularly preferred.

Further, such an organic silica thin film made of organic silica having an organic group capable of absorbing laser light in its skeleton may contain one type of organic group alone, or may contain two or more types of organic groups. It may contain a combination of organic groups. As the organic silica thin film containing two or more organic groups in combination, a plurality of types represented by any of the above general formulas (1-i) to (1-iv) and different types of X are and polymers of organosilicon compounds.

The polymer of at least one organosilicon compound selected from the compound group (A) described above should be used within a range that does not impair the effects of the present invention (for example, the thin film itself has a ratio of the mass of silicon to the mass of the organic group). The organosilicon compound for preparing the polymer may contain an organosilicon compound other than those selected from the compound group (A) as long as the conditions such as the ratio are satisfied. Such other organosilicon compounds include, for example, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane.

In addition, as such an organic silica thin film, a thin film having an uneven structure is used from the viewpoint that more sample molecules can be adsorbed more uniformly on the substrate surface in the range irradiated with laser light. It is more preferable to have The organic silica thin film having such an uneven structure should be a thin film having an uneven structure with a roughness factor of 1.4 or more (more preferably 1.7 or more, particularly preferably 2.0 or more) on the surface. is more preferred. If the roughness factor is less than the lower limit, the amount of laser light absorbed decreases, and the LDI support performance tends to decrease accordingly. The "roughness factor" means a value represented by actual surface area/geometric surface area. The value of such a roughness factor is obtained by measuring the surface shape of the organic silica thin film by SEM or AFM, calculating the surface area increase due to the provision of the uneven structure, and using that value, the uneven surface with respect to the smooth surface. can be obtained by calculating the ratio of the surface areas of

Further, when the organic silica thin film has an uneven structure, the uneven structure is preferably a porous structure in which pores composed of columnar voids are formed, or a pillar array structure in which columnar bodies are arranged. In addition, the "columnar shape" referred to here is not only a so-called columnar shape such as a substantially cylindrical column and a substantially polygonal column, but also a substantially conical shape, a substantially polygonal pyramid shape, etc., in which the size (diameter, length, etc.) of both ends is different. This is a concept that includes objects with different shapes. Such an uneven structure can be efficiently manufactured by nanoimprinting. For example, when the mold used for nanoimprinting has a pillar array structure, the porous structure to which the characteristics of the structure are transferred can be the concave-convex structure of the thin film. In the case where the thin film has a porous structure in which pores consisting of voids are formed, a pillar array structure in which the characteristics of the structure are transferred can be used as the uneven structure of the thin film. In addition, when forming an uneven structure by nanoimprinting (when forming an uneven structure that is a nanoimprint transfer structure), a mold having an uneven structure may be used to form an uneven structure by repeatedly transferring and reversing its characteristics. good.

In addition, as for such a concave-convex structure, the axial direction of the concave-convex structure is substantially perpendicular to the surface of the organic silica thin film opposite to the surface on which the concave-convex structure is formed. is preferred. This point will be briefly described with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

FIG. 2 is a schematic vertical cross-sectional view schematically showing a preferred embodiment of a structure (multilayer structure: laminate) comprising the organic silica thin film. The laminate (multilayer structure) shown in FIG. 2 includes a substrate 100 and an organic silica thin film 101 (the substrate 100 will be described later). Here, "the axial direction of the concave-convex structure is substantially perpendicular to the surface of the organic silica thin film opposite to the surface on which the concave-convex structure is formed" means, for example, the organic silica thin film 101 When the voids (the space of the recesses) of the uneven portion are columnar pores (when the organic silica thin film 101 has a porous structure), the direction of the long axis of the spatial shape of the pores (the shape of the voids) is It means that the organic silica thin film 101 is substantially perpendicular to the surface _S2 opposite to the surface _S1 of the organic silica thin film 101 on which the uneven structure is formed. When the projections are columnar bodies (pillar shape) (when the organic silica thin film 101 has a pillar array structure), the long axis direction of the columnar body (pillar shape) is aligned with the uneven structure of the organic silica thin film 101. It means that the surface _S1 on the present side is substantially perpendicular to the surface of the surface _S2 on the opposite side. Thus, the "axial direction of the uneven structure" refers to the direction of the long axis of the pores when the uneven structure is a porous structure, and the direction of the columnar bodies (pillars) when the uneven structure is a pillar array structure. It refers to the direction of the long axis. Further, the term "major axis" as used herein refers to the longitudinal axis passing through the shape of the void of the pore or the center of gravity of the columnar body, and can be determined based on the vertical cross-sectional view of the columnar body.

Here, the concept of "substantially perpendicular" will be described with reference to FIG. FIG. 3 is an enlarged view of region R shown in FIG. Here, taking as an example the case where the voids (spaces of the recessed portions) of the uneven portions shown in FIGS. To explain, the fact that the axial direction of the uneven structure is substantially perpendicular to the surface of the surface _S2 means that the surface _S2 of the organic silica thin film 101 opposite to the surface _S1 on which the uneven structure is formed. The angle α formed by the long axis C (long axis C of the pore) of the spatial shape of the pore (the columnar shape of the void) is 90°±30° (more preferably 90°±20°) with respect to the surface. is within the range of It should be noted that even when the projections are columnar (pillar-shaped) (when the organic silica thin film 101 has a pillar array structure), it is assumed that the axial direction of the uneven structure is substantially perpendicular to the surface of the surface _S2 . The angle formed by the major axis of the columnar body (pillar shape) with respect to the surface _S2 of the organic silica thin film 101 opposite to the surface _S1 on which the concave-convex structure is formed is 90°±30°. (more preferably 90°±20°).

Thus, in the uneven structure formed on the organic silica thin film 101, the axial direction of the uneven structure is substantially perpendicular to the surface _S2 of the organic silica thin film 101 (90°±30°, more preferably is 90°±20°) (the angle between the axial direction of the uneven structure and the surface of the surface _S2 of the organic silica thin film 101 is substantially perpendicular (90°±30°, more preferably 90°± 20°)). If the axial direction of the concave-convex structure formed in the organic silica thin film 101 is not in the above-mentioned direction, even if the laser beam is irradiated for mass spectrometry, the gaps of the concave-convex structure (in the case of pores, It tends to be difficult to desorb and evaporate the molecules adsorbed in the pore space) outside the membrane. In the case of the laminate (multilayer structure) shown in _FIG . It becomes a surface facing the surface of the material 100 . Whether or not the axial direction of the concave-convex structure is substantially perpendicular to the surface _S2 of the organic silica thin film 101 is determined as follows. That is, the cross section of the organic silica thin film is obtained by atomic force microscope (AFM) measurement, and the axial direction of the uneven structure at arbitrary 100 or more points is measured, and the uneven structure is formed in any axial direction. When it is substantially perpendicular (90° ± 30°, more preferably 90° ± 20°) to the surface of the surface opposite to the surface where the can be determined to be in a direction substantially perpendicular to the surface on the opposite side of the surface on which is formed.

In addition, such an organic silica thin film is a porous film having an uneven structure in which concave portions are formed by columnar pores, or a pillar array in which convex portions are formed by columnar bodies and the columnar bodies are arranged. A thin film having an uneven structure is preferable. That is, such an uneven structure may be an uneven structure in which the concave portions are formed by columnar pores, or an uneven structure in which the convex portions are formed by columnar bodies and composed of a pillar array in which the columnar bodies are arranged. A structure is preferred.

In such a concave-convex structure of the organic silica thin film, the average value of the distance between the wall surfaces of the convex portions is preferably 5 to 500 nm, more preferably 5 to 200 nm, and further preferably 5 to 100 nm. preferable. If the average value of the distance between the wall surfaces of such convex portions is less than the lower limit, it tends to be difficult to introduce and adsorb molecules with a large molecular weight into the uneven voids (pore spaces in the case of pores). On the other hand, when the above upper limit is exceeded, there is a tendency that the effect of increasing the surface area due to the formation of the uneven structure cannot be sufficiently obtained. In addition, the average value of the distance between the wall surfaces of such a convex portion is obtained by measuring the uneven structure using an atomic force microscope (AFM), obtaining a cross-sectional view (longitudinal cross-sectional view) of the uneven structure, and obtaining the cross-sectional view Based on, for any 100 or more convex portions, the position where the height of the convex portion is half the average height of the convex portion described later (the height of the convex portion used for measuring the distance between the wall surfaces The height position is obtained by considering the lowest point of the concave portion between the convex portion and the nearest convex portion as the height reference (height is 0 nm) for each convex portion). It can be obtained by obtaining the wall-to-wall distance (horizontal distance) between the convex portion and the nearest convex portion and calculating the average thereof. The distance between the wall surfaces (horizontal distance) between the nearest protrusions at the position where the height of the protrusions is half the average height of the protrusions described later is regarded as the distance between the protrusions. Therefore, even if the projection has a columnar shape with different sizes (diameter, length, etc.) at both ends, the distance between the columns can be measured. It is also possible to appropriately consider the design according to the type of the molecule to be measured to be introduced. In other words, the wall-to-wall distance between the protrusions can be used as an index of the size of the voids of the recesses. The distance between the wall surfaces of such projections can be regarded as the diameter of the pores when the recesses have an uneven structure formed of columnar pores. From this point of view, when the recesses have an uneven structure formed by columnar pores, the average pore diameter of the pores is 5 to 500 nm (more preferably 5 to 200 nm, more preferably 5 to 500 nm). 100 nm). Similarly, when the protrusions are formed of pillars and the protrusions have a pillar array in which the pillars are arranged, the distance between the wall surfaces of the protrusions (between the pillars distance) is preferably 5 to 500 nm (more preferably 5 to 200 nm, still more preferably 5 to 100 nm).

Further, in such an uneven structure of the organic silica thin film, the average height of the protrusions (average depth of the recesses) is preferably equal to or greater than the average distance between the wall surfaces of the protrusions, and is 20 to 1500 nm. is more preferable, and 50 to 500 nm is particularly preferable. It is more preferable that the average height of the projections (average depth of the recesses) is in the same range as the thickness T of the film described later. If the average height of the protrusions (average depth of the recesses) is less than the lower limit, the effect of increasing the surface area due to the formation of the uneven structure tends to be insufficient. is used for mass spectrometry, it is difficult to desorb and evaporate the molecules adsorbed in the deep part of the pores (in the pore space in the case of pores) outside the membrane even if laser light is irradiated. tend to become The average height of the protrusions (average depth of the recesses) referred to here is obtained by measuring the uneven structure using an atomic force microscope (AFM) and obtaining a cross-sectional view (longitudinal cross-sectional view) of the uneven structure. Based on the cross-sectional view, for any 100 or more convex portions, the difference between the lowest point (the lowest point of the concave portion) among the adjacent concave portions and the height of the apex of the convex portion ( It can be obtained by obtaining the vertical distance) and calculating the average.

In addition, the average pitch of the uneven structure is preferably 20 to 1000 nm, more preferably 20 to 500 nm, even more preferably 20 to 200 nm. If the average pitch of such unevenness is less than the lower limit, it tends to be difficult to produce a textured structure with a high aspect ratio. There is a tendency. As such an average pitch, the uneven structure is measured using an atomic force microscope (AFM), a cross-sectional view (longitudinal cross-sectional view) of the uneven structure is obtained, and based on the cross-sectional view, any 100 points or more With respect to the convex portion, between the convex portion and the nearest convex portion, the vertex of the convex portion (the cross-sectional shape of the convex portion is a shape such as a substantially rectangular shape, and the upper portion of the convex portion is a straight line that includes the vertex of the convex portion (For example, if the convex part is cylindrical and the upper part is flat), measure the horizontal distance between the center points of the upper part) and calculate the average of each measured value. adopt.

When the uneven structure of such an organic silica thin film is a pillar array in which the protrusions are formed by columnar bodies and the columnar bodies are arranged, the average length of the short axis of the columnar bodies is It is preferably 10 to 500 nm, more preferably 10 to 200 nm, even more preferably 10 to 150 nm. If the average length of the minor axis is less than the lower limit, it tends to be difficult to produce a textured structure with a high aspect ratio. tend not to be The length of the short axis of such a columnar body is determined by measuring the uneven structure using an atomic force microscope (AFM), obtaining a cross-sectional view (longitudinal cross-sectional view) of the uneven structure, and based on the cross-sectional view, It can be obtained by obtaining the length of the short axis of the columnar body at arbitrary 100 points or more and calculating the average. The short axis of the columnar body here means an axis that passes through the center of gravity of the columnar body and is perpendicular to the long axis, and can be obtained based on the vertical cross-sectional view of the columnar body.

Further, in the present invention, the organic silica thin film contains 0.5 to 4.0 atomic % of titanium oxide in terms of titanium element ratio in a region within a range of 10 nm in the depth direction from the surface of the organic silica thin film. There is. If the content of such titanium oxide (the aforementioned titanium element ratio) is less than the lower limit, the formation of adsorption sites for sample molecules is insufficient, and the uniformity of the signal intensity of the substance to be analyzed within the analysis region decreases. On the other hand, if the above upper limit is exceeded, the absorption of laser light by the organic groups and the transmission of the energy generated by such absorption of the laser light to the substance to be analyzed will be inhibited. In addition, while sufficiently suppressing the absorption of laser light by the organic groups and the inhibition of the transmission of the energy generated by such absorption of the laser light to the substance to be analyzed, the adsorption sites of the sample molecules are formed more uniformly. From the fact that it is possible to make it possible, it is possible to contain 0.7 to 3.0 at % of titanium oxide in a region within a range of 10 nm in the depth direction from the surface of the organic silica thin film. More preferably, the content is 1.0 to 2.0 at %.

In the present invention, the titanium element ratio (the titanium element ratio of the titanium oxide contained in a region within a range of 10 nm in the depth direction from the surface of the organic silica thin film [unit: at %]) adopts the value obtained as follows. That is, such a titanium element ratio exists within a range of up to 10 nm in the depth direction from the surface of the organic silica thin film, which is detected by X-ray photoelectron spectroscopy (XPS). The content ratio (atomic ratio) of all the elements to be measured is obtained, and the content ratio of the titanium element to the total amount of all the elements to be measured (atomic ratio: element composition ratio of the titanium element) is adopted. Such XPS is a method that can be used to examine the ratio of elements in a region within about 10 nm in the depth direction from the outermost surface of a substance. In addition, the content of elements (for example, silicon, carbon, oxygen, nitrogen, titanium, etc., although it varies depending on the type of organic group) contained within a range of up to 10 nm in the depth direction from the surface of the organic silica thin film. Since the (atomic ratio) can be analyzed by a commercial XPS device (hydrogen is not detectable), the amount of all elements (all elements except hydrogen) present in the region that can be measured by such a commercial XPS device ( atomic weight), and the ratio of the titanium element to the total amount (atomic %: element composition ratio of the titanium element). The measurement method, type of measurement device, measurement conditions, etc. are not particularly limited as long as similar results can be obtained. It is preferable to adopt the following measurement conditions using .
[Measurement conditions for X-ray photoelectron spectroscopy]
X-ray source: AlKα, 1486.6ev
Photoelectron extraction angle: 45°
Analysis region: 100 μm diameter region Pass energy: 93.8 eV
Energy step: 0.2 eV.

Further, in the present invention, the organic silica thin film preferably has a hydrophobic group on its surface. By having such a hydrophobic group, the liquid contact area can be made smaller when the sample solution containing the substance to be analyzed is dropped onto the thin film, and the carrying density of the substance to be analyzed can be increased, and during LDI-MS, It becomes possible to further improve the signal intensity of the substance to be analyzed.

From the viewpoint of hydrophobicity, such a hydrophobic group is preferably a group having an aliphatic carbon skeleton as a main skeleton (hydrophobic group). Here, the “aliphatic carbon skeleton” includes a portion having a carbon skeleton structure similar to that of aliphatic hydrocarbons, and a structure (skeleton) having a plurality of carbon atoms (C) in the skeleton. It may be a skeleton formed only by carbon atoms of aliphatic hydrocarbons, or a skeleton formed by bonding carbon atoms of aliphatic hydrocarbons and other atoms (hetero atoms) (fatty It may also be a skeleton having a structure in which at least part of the carbon atoms of the family hydrocarbon is substituted with a heteroatom (for example, an oxygen atom, a nitrogen atom, etc.).

Although such a hydrophobic group is not particularly limited, at least one group selected from the group consisting of an alkyl group, a fluorine atom-containing group, and an alkoxy group is preferable.

Examples of fluorine atom-containing groups suitable as such hydrophobic groups include fluoroalkyl groups and fluoroether groups. Here, the fluoroalkyl group means an alkyl group in which at least part of hydrogen atoms are substituted with fluorine atoms (an alkyl group or a perfluoroalkyl group in which hydrogen atoms are partially substituted with fluorine atoms). The number of carbon atoms (the number of carbon atoms in the alkyl chain) of the main skeleton (carbon skeleton) of such a fluoroalkyl group (an alkyl group in which at least part of the hydrogen atoms are substituted with fluorine atoms) is 3 or more (more preferably 4 or more, 5 or more) is particularly preferable. If the number of carbon atoms is less than the above lower limit, there is a tendency that sufficient hydrophobicity cannot be obtained. _{Such fluoroalkyl groups include , for example , the _ _} , CF ₃ -CF ₂ -CF ₂ -, CF ₃ -CF ₂ -CH ₂ -CH ₂ -, F-CH ₂ -CF ₂ -CH ₂ -CH ₂ -, CF ₂ (CF ₃ )-CH ₂ -CH A group represented by _2- and the like can be mentioned.

Further, a fluoroether group suitable as the fluorine atom-containing group is represented by the following general formula (i):

[In formula (i), R ¹⁰ represents a divalent alkylene group (fluorinated alkylene group) in which at least part of the hydrogen atoms are substituted with fluorine atoms. ]
A group having a structure represented by R ¹⁰ (alkylene group in which at least part of the hydrogen atoms are substituted with fluorine atoms (fluorinated alkylene group)) in formula (i) has the following general formula (ii):
_{-CnF2n- (} ii)
[In formula (ii), n represents an integer of 1 to 20 (preferably 1 to 10, more preferably 1 to 5, particularly preferably 1 to 3). ]
A divalent perfluoroalkylene group represented by is more preferable. Suitable structures represented by formula (i) include, for example, the formulas: -CF ₂ -O-, -CF ₂ -CF ₂ -O-, -CF ₂ -CF ₂ -CF ₂ - A group represented by O— and the like can be mentioned.

Examples of the fluoroether group having the structure represented by formula (i) include the following general formula (iii):

[In formula (iii), R ²⁰ represents any one of a hydrogen atom, a fluorine atom, a methyl group, and a trifluoromethyl group, and R ¹⁰ has the same definition as R ¹⁰ in the general formula (i); , a represents an integer of 1 to 200 (number of repetitions), R ²¹ represents a divalent alkylene group or a divalent alkylene group in which at least part of the hydrogen atoms are substituted with fluorine atoms (fluorinated alkylene group) show. ]
A group represented by can be exemplified as a suitable one. Considering the high hydrophobicity of the fluorinated alkyl group, R ²⁰ in such formula (iii) is more preferably a trifluoromethyl group or a fluorine atom. In addition, a divalent alkylene group as R ²¹ has the formula: —C _n H _2n — [wherein n is an integer (more preferably any integer from 1 to 10, more preferably from 1 to 5 any integer of 1 to 3, particularly preferably any integer of 1 to 3). ] is a group represented by Further, the divalent fluorinated alkylene group as R ²¹ may be a group represented by the formula: —C _n H _2n — in which at least part of the hydrogen atoms are substituted with fluorine atoms. Examples include, but are not limited to, formulas: -CF ₂ -, -CF(CF ₃ )-, -CH ₂ -CF ₂ -, -CF ₂ -CF ₂ -, -CF ₂ -CF ₂ -CH ₂ -CH ₂ Groups represented by -, -CH ₂ -CF ₂ -CH ₂ -CH ₂ -, and -CF(CF ₃ )-CH ₂ -CH ₂ - are preferred.

Each such hydrophobic group may also contain a side chain. From the viewpoint of hydrophobicity, the group capable of forming such a side chain is preferably at least one group selected from the group consisting of an alkyl group, a fluorinated alkyl group, a fluoroether group, and an alkoxy group. . As the hydrophobic group containing such a side chain, for example, at least part of the atoms (e.g., hydrogen atoms and halogen atoms) bonded to the aliphatic carbon skeleton forming the main skeleton of the hydrophobic group is A group substituted with a group capable of forming the side chain (at least one group selected from the group consisting of an alkyl group, a fluorinated alkyl group, a fluoroether group, and an alkoxy group) can be exemplified. .

In addition, such a hydrophobic group can be introduced to the surface of the organic silica thin film by using, for example, a hydrophobic material (hydrophobic material having the hydrophobic group) described later, and A layer may be formed on the surface of the organic silica thin film. The hydrophobic material and its introduction method will be described later.

The thickness T of such an organic silica thin film is preferably 20 to 2000 nm, more preferably 50 to 1000 nm, even more preferably 100 to 500 nm. If the thickness is less than the lower limit, the laser beam cannot be sufficiently absorbed when used as a substrate for mass spectrometry, and the efficiency of desorption and ionization of molecules to be measured tends to decrease. When the upper limit is exceeded, when the laser beam does not reach the deep part of the thin film when used as a substrate for mass spectrometry, and the molecule to be measured is adsorbed in the deep part, the efficiency of desorption and ionization of the molecule to be measured tends to decline.

Further, the organic silica substrate of the present invention may be in the form of a laminate in which the organic silica thin film is laminated on a substrate 100, as shown in FIGS. 2 and 3, for example. Such a substrate is not particularly limited as long as it can support the organic silica thin film. Examples include silicon substrates (Si substrates), quartz substrates, glass substrates, and various metals. Known substrates that can be used in producing a silica film, such as substrates and various thin films, can be used as appropriate. Although the form of such a substrate is not particularly limited, a flat substrate is preferable.

The method that can be suitably used for producing such an organic silica substrate of the present invention is not particularly limited. A sol solution obtained by partially polymerizing an organosilicon compound selected from group (A)) is used to form a coating film of the sol solution on the substrate, followed by and applying titanium alkoxide and tetraalkoxysilane to the surface of the organic silica thin film obtained in the first step in a depth direction of 10 nm from the surface of the organic silica thin film. Titanium oxide is contained on the surface of the organic silica thin film by contacting and reacting so that 0.5 to 4.0 atomic % of titanium oxide is contained in the range of up to and a second step of obtaining the organic silica substrate of the present invention by forming a layer (hereinafter, for convenience, the method including such first and second steps is simply referred to as "method (I)". ) can be adopted. In the case where the method (I) is employed, for example, in the first step, after forming a coating film using the sol solution and before it is completely cured, the coating film is formed with an uneven structure by nanoimprinting. Then, by curing, it is possible to obtain a porous film (organic silica thin film) having the uneven structure described above. Further, when the method (I) is employed, for example, in the second step, when the titanium alkoxide and tetraalkoxysilane are brought into contact with the surface of the organic silica thin film, a hydrophobic material is also brought into contact at the same time. The layer made of titanium oxide may be a layer containing titanium oxide; be. Hereinafter, such method (I) will be briefly described separately for the first step and the second step.

(First step)
The first step of such method (I) is the organosilicon compound having an organic group capable of absorbing laser light (more preferably, one organosilicon compound selected from the compound group (A)) A sol solution obtained by partially polymerizing is used to form a coating film of the sol solution on the substrate, followed by curing to obtain an organic silica thin film.

The sol solution (colloidal solution) used in the first step is obtained by partially polymerizing the organosilicon compound having an organic group capable of absorbing laser light. Such a sol solution is a so-called sol in the field of producing silica structures, except that the organosilicon compound (more preferably, one organosilicon compound selected from the compound group (A)) is used. - can be suitably formed by employing a known method known as the gel method; Such a sol solution is preferably a solution containing a partial polymer obtained by partially hydrolyzing and condensing the organosilicon compound. The solvent used for such a solution is not particularly limited, and a known solvent used in the so-called sol-gel method can be appropriately used. ), acetone, tetrahydrofuran, N,N-dimethylformamide, 1,4-dioxane and acetonitrile. Among such solvents, methoxyethanol, 1-propanol, 2-propanol, 1,4-dioxane, and tetrahydrofuran are preferred from the viewpoint of volatility around room temperature and high solubility of organic compounds.

Further, when preparing such a sol solution, the conditions (temperature and reaction time) for partially polymerizing the organosilicon compound are not particularly limited, and depending on the type of the organosilicon compound used, for example, , the reaction temperature may be about 0 to 100° C., and the reaction time may be about 5 minutes to 24 hours. Moreover, from the viewpoint of allowing such partial polymerization to proceed efficiently, it is preferable to use an acid catalyst. Examples of such acid catalysts include mineral acids such as hydrochloric acid, nitric acid and sulfuric acid.

As a method for preparing such a sol solution, for example, a solution containing the organosilicon compound, the solvent, and the acid catalyst is prepared, and the solution is heated to room temperature (20 to 28°C, preferably 25°C). for about 0.5 to 12 hours to partially polymerize (partially hydrolyze and partially polycondense) the organosilicon compound to prepare a sol solution. In the case where the reaction is carried out by stirring as described above, if the stirring time is less than the lower limit, the hydrolysis reaction of the silyl groups becomes insufficient, and the curing reaction of the formed film tends to be difficult to proceed.

Note that the sol solution contains other organosilicon compounds other than the above organosilicon compounds (eg, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane, etc.) within a range that does not impair the effects of the present invention. It may be contained further.

As for the sol solution, the content of the organosilicon compound in the solvent is preferably 0.2 to 20% by mass, more preferably 0.5 to 7% by mass. If the content of the organosilicon compound is less than the lower limit, it tends to be difficult to produce a uniform film while controlling the thickness. It tends to be difficult to prepare a stable sol solution.

Furthermore, in such a sol solution, the content of the organosilicon compound in the solvent is preferably 2 to 200 g/L, more preferably 5 to 100 g/L. If the content of the organosilicon compound is less than the lower limit, it tends to be difficult to produce a uniform film while controlling the thickness. It tends to be difficult to prepare a stable sol solution.

In addition, such a sol solution is formed by partially polymerizing the organosilicon compound, and then filtered with a membrane filter or the like from the viewpoint of preventing contamination during production and ensuring higher smoothness. It is preferable to use

The method of forming the coating film obtained from the sol solution is not particularly limited, and a method of casting the sol solution into a mold or a method of coating the base material by various coating methods is preferably employed. Furthermore, as such a coating method, a known method (for example, a method of coating using a bar coater, a roll coater, a gravure coater, etc., a method such as dip coating, spin coating, spray coating, etc.) can be appropriately adopted. can.

The thickness of the film (uncured or semi-cured) obtained from such a sol solution is preferably 0.1 to 100 μm, more preferably 0.1 to 25 μm. If the thickness of such a film is less than the lower limit, it tends to be difficult to keep the thickness of the film uniform over the entire surface of the substrate. It is in.

In addition, as a method for curing such a coating film, depending on the type of the organosilicon compound used, conditions may be appropriately adopted such that the hydrolysis and condensation reactions proceed, and the temperature, heating time, etc. is not particularly limited, but it is preferable to heat at a temperature of about 25 to 150° C. for a time of about 1 to 48 hours. By heating in this manner, the hydrolysis and condensation reactions of the organosilicon compound and/or the partially polymerized organosilicon compound can be further advanced, thereby forming a coating film obtained from the sol solution. It becomes possible to form the organic silica thin film by curing. In such a curing step, in order to allow the hydrolysis of the remaining alkoxy groups and the curing of the thin film to proceed more efficiently, the coating film is heated in the above temperature range (25 to 150 ° C.) while heating from 1 to 1 Exposure to hydrochloric acid vapors for about 48 hours is preferred. By exposure to such hydrochloric acid vapor, it is possible to promote the reaction not only on the surface of the coating film but also on the inside, and it is possible to proceed more efficiently with hydrolysis of the remaining alkoxy groups and curing of the thin film. It is also possible to expose hydroxyl groups on the surface of the obtained thin film, and in the second step, it is possible to react such hydroxyl groups with titania alkoxide more efficiently, and in some cases, to react with a hydrophobic material. .

In such a first step, as described above, after forming a coating film using the sol solution, before curing, the coating film is formed with an uneven structure by nanoimprinting, and then cured. Thus, the obtained organic silica thin film can be made into a porous film (organic silica thin film) having an uneven structure. In this way, when the nanoimprinting step (the step of forming a concave-convex structure by nanoimprinting and curing it) is employed in the first step, the effects of structural shrinkage due to evaporation of the solvent in the nanoimprinting step should be minimized. , the film obtained from the sol solution is treated by volatilizing (removing) the solvent in the coating process using a volatile solvent, even if the film has been treated to remove the solvent. It may be a film obtained by In the coating film obtained from such a sol solution, most of the solvent may evaporate (volatilize) in the process of forming the film (coating process, etc.) depending on the type of solvent used in the sol solution. In this case, it is possible to minimize the effect of structural shrinkage due to evaporation (volatilization) of the solvent without performing any special treatment to remove the solvent. In addition, for the “nanoimprint” referred to herein, a known technique known as a so-called nanoimprint method can be appropriately adopted, and a mold (nanostructure) on which a fine uneven pattern is formed is used to form a pattern of the mold. It is possible to appropriately adopt a method of transferring (nanoimprint method).

As a mold used for such nanoimprinting, a mold that can be used for a known nanoimprinting method can be appropriately used, and a commercially available product may be used. Moreover, as such a mold (nanostructure), any mold having a desired uneven structure, such as a nanostructure having a fine uneven pattern, can be appropriately used.

As a mold used for such nanoimprinting, the axial direction of the uneven structure of the organic silica thin film to be formed is substantially perpendicular to the surface of the organic silica thin film opposite to the surface on which the uneven structure is formed. It is preferable that it has an uneven structure that provides a direction. By using such a mold, the unevenness characteristics of the mold are transferred, and the axial direction of the unevenness structure is a direction substantially perpendicular to the surface of the thin film opposite to the surface on which the unevenness structure is formed. Thus, it becomes possible to efficiently produce an organic silica thin film having an uneven structure. For example, when a flat plate on which an uneven structure is formed is used as a mold, the uneven structure of the mold is placed on the surface of the flat plate opposite to the surface on which the uneven structure is formed. When the concave-convex pattern of the mold is transferred, the axial direction of the concave-convex structure formed on the organic silica thin film is more efficiently aligned with the direction of the organic silica thin film. The direction can be substantially perpendicular to the surface opposite to the surface on which the uneven structure is formed.

In addition, the concave-convex structure of the mold used for such nanoimprinting is a concave-convex structure consisting of a pillar array in which the convex portions are formed by columnar bodies and the columnar bodies are arranged, or a concave-convex structure in which the concave portions are formed by columnar pores. It is preferable that the concave-convex structure is In addition, since the concave-convex structure of such a mold is used to transfer (reverse) the characteristics of the concave-convex structure by nanoimprinting to form the concave-convex structure on the organic silica thin film, the concave-convex structure is suitable for the mold. The conditions are the same as the various conditions (e.g., average pore diameter, average pitch, etc.) described above for the uneven structure of the organic silica thin film.

In addition, as a method of forming an uneven structure by nanoimprinting and curing it, a film obtained from the sol solution (a coating film of the sol solution (uncured or semi-cured), a treatment of removing the solvent from the coating film of the sol solution, etc. After the mold is placed on the surface of the film (which may be uncured or semi-cured), so that the characteristics of the unevenness formed on the mold are transferred (inverted), the mold It is preferable to employ a method in which the film obtained from the sol solution is cured by heating while it is placed thereon. After removing the mold from the thin film cured by heating in this manner, the thin film is treated with hydrochloric acid vapor from the viewpoint of sufficiently advancing the hydrolysis of the alkoxy groups remaining in the thin film and the curing of the thin film. may be exposed. In this way, the porous film can be efficiently formed by nanoimprinting, and it can be used as the organic silica thin film.

(Second step)
In the second step of method (I), titanium alkoxide and tetraalkoxysilane are applied to the surface of the organic silica thin film obtained in the first step in a region of up to 10 nm in the depth direction from the surface of the organic silica thin film. is brought into contact with titanium oxide so that it contains 0.5 to 4.0 at% of titanium element ratio, and then reacted to form a layer containing titanium oxide on the surface of the organic silica thin film, This is the step of obtaining the organic silica substrate of the present invention.

The titanium alkoxide used in such a second step is not particularly limited, but is capable of forming a layer containing titanium oxide (a region near the surface containing titanium oxide) more efficiently on the surface of the organic silica thin film. Tetraalkoxytitanium is preferred because it is possible to Examples of such tetraalkoxytitanium include tetraethoxytitanium, tetrapropoxytitanium, and tetrabutoxytitanium. Among them, tetraalkoxytitanium is used to bring the titanium alkoxide into contact with the surface of the organic silica thin film. When a method of evaporating and contacting the vapor is employed, tetraethoxytitanium and tetrapropoxytitanium are more preferable, and tetraethoxytitanium is particularly preferable, since those having a lower boiling point and higher hydrolytic reactivity are desirable. .

The tetraalkoxysilane used in the second step is not particularly limited, but when a method of evaporating tetraalkoxytitanium and bringing the vapor into contact with the surface of the organic silica thin film is employed. Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetraisopropoxysilane are preferred, and tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane are preferred because those having a lower boiling point and higher hydrolysis reactivity are desirable. More preferred are tetramethoxysilane and tetraethoxysilane.

In the case of introducing a hydrophobic group onto the surface of the organic silica thin film (when the organic silica thin film has a hydrophobic group on the surface), titanium alkoxide and tetraalkoxysilane are added onto the surface of the organic silica thin film. At the time of contact, it is preferable to bring the aforementioned hydrophobic material having a hydrophobic group into contact with the surface of the organic silica thin film together with the titanium alkoxide and tetraalkoxysilane.

As such a hydrophobic material, a hydrophobic material having the aforementioned hydrophobic group and a functional group capable of covalently bonding with the silica skeleton of the organic silica is preferable. The functional group that can be covalently bonded to the silica skeleton of such organic silica is not particularly limited, but for example, the following general formula (iv):
Me-Z (iv)
[In formula (iv), Me represents a metal atom other than titanium, and Z represents a hydrolyzable substituent. ]
A group having a structural portion represented by is mentioned.

Examples of Me in such formula (iv) include a silicon atom and the like. Moreover, such hydrolyzable substituents are not particularly limited, and include halogen atoms, alkoxy groups, and the like. Formula for such a hydrolyzable substituent: As a group represented by -Z, since it becomes easier to control hydrolysis reactivity and boiling point, the following general formula (v):
-OR ³⁰ (v)
[R ³⁰ represents an alkyl group having 1 to 5 carbon atoms (more preferably 1 to 3, particularly preferably 1 to 2 carbon atoms). ]
An alkoxy group represented by is more preferable. If the number of carbon atoms in R ³⁰ exceeds the above upper limit, the hydrolysis reactivity is lowered and the boiling point is raised. is vaporized and the vapor is contacted, the amount of vaporization tends to decrease at the treatment temperature.

In addition, since the alkoxy group represented by the formula: -OR ³⁰ has a structural portion bonded to the metal atom (Me), the hydroxyl group (-OH) on the organic silica thin film can be easily hydrolyzed. This makes it possible to more efficiently introduce the metal atom (Me) via oxygen into the silicon atom (Si) forming the silica skeleton (formula: Me—O -Si (Si in this formula is a silicon atom that forms a silica skeleton) can be formed more efficiently), the silica skeleton of the organic silica that forms the organic silica thin film, and the hydrophobic This makes it possible to react (covalently bond) organic materials more efficiently.

Further, when the metal atom (Me) is a silicon atom, the functional group capable of covalently bonding with the silica skeleton of such organic silica may be, for example, the following general formula (vi):
—Si(Z) _3-x (R ³⁰ ) _x (vi)
[In the formula (vi), Z has the same definition as Z in the formula (iv) (more preferably an alkoxy group represented by the above formula (v): R ^O- ), and ^R It has the same definition as R ³⁰ in (v), and x represents an integer of 0 to 2 (preferably 0 to 1, more preferably 0). ]
A group represented by is preferred.

As the hydrophobic material having a functional group capable of covalently bonding with the silica skeleton of the organic silica, when the metal atom (Me) in the formula (iv) is a silicon atom, the hydrolyzed Depending on the decomposable substituent (Z), for example, trimethoxy(3,3,3-trifluoropropyl)silane, trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane, triethoxy(1H, Fluorinated alkyltrialkoxysilanes such as 1H,2H,2H-tridecafluorooctyl)silane); trifluoroalkyldialkylchlorosilanes such as trifluoropropyldimethylchlorosilane; trialkylchlorosilanes such as trimethylchlorosilane, triethylchlorosilane, tripropylchlorosilane; Preferred examples include silane compounds containing hydrophobic groups such as (ptadecafluoro-1,1,2,2-tetrahydrodecyl)dimethylchlorosilane.

Examples of such hydrophobic materials include metal alkoxides having the above-mentioned hydrophobic groups, silicone resins having the above-mentioned hydrophobic groups in side chains and having functional groups capable of covalently bonding with silica skeletons, and trialkylsilanes containing halogen atoms. Suitable examples include compounds (chlorotrialkylsilane, iodotrialkylsilane, etc.). As such a hydrophobic material, a metal alkoxide having the hydrophobic group is particularly preferable from the viewpoint of easier control of hydrolysis reactivity and boiling point. As such a metal alkoxide having a hydrophobic group, it is more preferable to be an alkoxysilane compound having the above-mentioned hydrophobic group, and since it is possible to form a more stable bond with the silica skeleton, the following general formula (vii):
D-Si(OR ³⁰ ) ₃ (vii)
[In the formula, R ³⁰ has the same definition as R ³⁰ in the above formula (v), and D represents the hydrophobic group. ]
An alkoxysilane compound represented by is particularly preferred.

In the second step, the method for bringing the titanium alkoxide and the tetraalkoxysilane into contact with the surface of the organic silica thin film includes, for example, titanium alkoxide and tetraalkoxysilane (and, if necessary, the hydrophobic material ) on the surface of the organic silica thin film (for example, a method of applying the solution by spraying or the like), introducing the organic silica thin film into a sealable container, and removing the titanium alkoxide and tetra A method of exposing to vapor of alkoxysilane (optionally including vapor of the hydrophobic material) can be employed as appropriate.

Thus, the amount of the titanium alkoxide used when the titanium alkoxide and the tetraalkoxysilane are brought into contact with the surface of the organic silica thin film (the amount used) is 10 nm in the depth direction from the surface of the organic silica thin film. From the viewpoint of contacting the titanium alkoxide and the tetraalkoxysilane so that the titanium oxide is contained in the range of 0.5 to 4.0 at% in terms of titanium element ratio, the titanium alkoxide and the tetraalkoxy It is preferably 15 to 30% by mass (more preferably 20 to 25% by mass) relative to the total amount of silane. If the amount of titanium alkoxide used is less than the above lower limit, the introduction amount of titanium oxide is insufficient, making it difficult to form sufficient adsorption sites, and the uniformity of the signal intensity of the substance to be analyzed within the analysis area decreases. On the other hand, when the above upper limit is exceeded, the amount of titanium oxide introduced increases, which inhibits the absorption of laser light by organic groups and the transmission of energy generated by the absorption of laser light to the substance to be analyzed. may reduce the signal intensity of the analyte during mass spectrometry.

Further, the amount of the titanium alkoxide used when the titanium alkoxide and the tetraalkoxysilane are brought into contact with the surface of the organic silica thin film (the amount used) is set to a depth of up to 10 nm from the surface of the organic silica thin film. From the viewpoint of contacting the titanium alkoxide and the tetraalkoxysilane so that the titanium oxide is contained in the range of 0.5 to 4.0 at% in terms of titanium element ratio, the titanium alkoxide and the tetraalkoxysilane 10 to 25 atm in terms of metal element ([amount of titanium in the titanium alkoxide]/([amount of titanium in the titanium alkoxide] + [amount of silicon in the tetraalkoxysilane])) with respect to the total amount of % (more preferably 15 to 20 at %). If the amount of titanium alkoxide used is less than the above lower limit, the introduction amount of titanium oxide is insufficient, making it difficult to form sufficient adsorption sites, and the uniformity of the signal intensity of the substance to be analyzed within the analysis area decreases. On the other hand, when the above upper limit is exceeded, the amount of titanium oxide introduced increases, inhibiting the absorption of laser light by organic groups and the transmission of the energy generated by the absorption of laser light to the substance to be analyzed, This may reduce the signal intensity of the analyte during mass spectrometry.

Further, when the hydrophobic material is used together with the titanium alkoxide and the tetraalkoxysilane, the titanium used when the titanium alkoxide, the tetraalkoxysilane and the hydrophobic material are brought into contact with the surface of the organic silica thin film. The amount (usage amount) of the alkoxide is such that the titanium oxide is contained in a range of 10 nm in the depth direction from the surface of the organic silica thin film in an amount of 0.5 to 4.0 at % in terms of titanium element ratio. From the viewpoint of bringing these components into contact with each other, the mass ratio is 15 to 30% by mass (more preferably 20 to 25% by mass) with respect to the total amount of the titanium alkoxide, the tetraalkoxysilane, and the hydrophobic material. is preferred. If the amount of titanium alkoxide used is less than the above lower limit, the introduction amount of titanium oxide is insufficient, making it difficult to form sufficient adsorption sites, and the uniformity of the signal intensity of the substance to be analyzed within the analysis area decreases. On the other hand, when the above upper limit is exceeded, the amount of titanium oxide introduced increases, inhibiting the absorption of laser light by organic groups and the transmission of the energy generated by the absorption of laser light to the substance to be analyzed, This may reduce the signal intensity of the analyte during mass spectrometry.

Further, when the hydrophobic material is used together with the titanium alkoxide and the tetraalkoxysilane, and the hydrophobic material is the alkoxysilane compound represented by the formula (vii), the titanium alkoxide, the tetraalkoxysilane and The amount (use amount) of the titanium alkoxide used when the hydrophobic material is brought into contact with the surface of the organic silica thin film is such that titanium With respect to the total amount of the titanium alkoxide, the tetraalkoxysilane, and the hydrophobic material, from the viewpoint of contacting these components so that the oxide is contained in an amount of 0.5 to 4.0 at% in terms of titanium element ratio, , in terms of metal elements ([amount of titanium in the titanium alkoxide]/([amount of titanium in the titanium alkoxide] + [amount of silicon in the tetraalkoxysilane] + [amount of silicon in the hydrophobic material ])) is preferably 5 to 20 at % (more preferably 10 to 15 at %). If the amount of titanium alkoxide used is less than the above lower limit, the introduction amount of titanium oxide is insufficient, making it difficult to form sufficient adsorption sites, and the uniformity of the signal intensity of the substance to be analyzed within the analysis area decreases. On the other hand, when the above upper limit is exceeded, the amount of titanium oxide introduced increases, inhibiting the absorption of laser light by organic groups and the transmission of the energy generated by the absorption of laser light to the substance to be analyzed, This may reduce the signal intensity of the analyte during mass spectrometry. When the hydrophobic material is used together with the titanium alkoxide and the tetraalkoxysilane, the content of the tetraalkoxysilane is set relative to the total amount of the titanium alkoxide, the tetraalkoxysilane, and the hydrophobic material. , in terms of metal elements ([amount of silicon in the tetraalkoxysilane]/([amount of titanium in the titanium alkoxide] + [amount of silicon in the tetraalkoxysilane] + [silicon in the hydrophobic material amount])) is preferably 60 to 90 at % (more preferably 70 to 80 at %).

In the second step, as a method for bringing the titanium alkoxide and the tetraalkoxysilane into contact with the surface of the organic silica thin film, the organic silica thin film is introduced into a sealable container, and the titanium alkoxide and the tetraalkoxysilane are When exposed to vapor of alkoxysilane (optionally including vapor of the hydrophobic material), for example, after introducing the organic silica thin film into a sealable container, the sealable container has an opening. The titanium alkoxide and tetraalkoxysilane (and optionally the hydrophobic material) are introduced (i.e., the titanium alkoxide and tetraalkoxysilane (and A separate container having an opening in which the hydrophobic material is added) was introduced into the sealable container into which the organic silica thin film was introduced), and then the sealable container was sealed. After that, a method of exposing the surface of the organic silica thin film to the vapor of the titanium alkoxide and tetraalkoxysilane (including the vapor of the hydrophobic material in some cases) by heating (hereinafter, for convenience, sometimes simply "method (i)”) can be adopted.

A sealable container for introducing such an organic silica thin film is not particularly limited, and a known container can be appropriately used. Also, the material of such a sealable container is not particularly limited, and for example, a container made of fluororesin (for example, Teflon (registered trademark)) may be used as appropriate.

Further, in the case of adopting the method (i) as described above, the sealable container has an opening to which the titanium alkoxide and the tetraalkoxysilane (and the hydrophobic material as necessary) are added. The sealable container is sealed after introducing another container having In such a step, the titanium alkoxide and tetraalkoxysilane (and the hydrophobic material as necessary) are added from the viewpoint of controlling the hydrolysis reaction and dehydration condensation reaction of the titanium alkoxide and tetraalkoxysilane. It is preferable that the gas atmosphere is an inert gas (eg, argon, nitrogen, etc.) atmosphere (inert gas atmosphere) when introducing another container having an opening where the gas is contained. Further, even after the sealable container is sealed, the gas atmosphere in the container is preferably an inert gas atmosphere from the viewpoint of controlling the hydrolysis reaction and dehydration condensation reaction of titanium alkoxide and tetraalkoxysilane.

In the case of adopting method (i), the conditions for heating after sealing the sealable container are not particularly limited, but in an inert gas atmosphere, 120 to 180 ° C. ° C.) for 0.5 to 1.5 hours (more preferably 0.8 to 1.2 hours). If the heating temperature and heating time are less than the above lower limits, the introduction amount of titanium oxide is insufficient, and the titanium oxide, which is the adsorption site for the target substance, is not sufficiently formed. On the other hand, if the above upper limit is exceeded, the amount of titanium oxide introduced increases, and the absorption of laser light by organic groups or the energy generated by the absorption of laser light is the substance to be analyzed. transmission to , which may reduce the signal strength of the analyte during mass spectrometry.

By adopting such method (i), the surface of the organic silica thin film is more uniformly exposed to the vapor of the titanium alkoxide and the tetraalkoxysilane (including the vapor of the hydrophobic material in some cases). It becomes possible to Further, by exposing the surface of the organic silica thin film to the vapor of the titanium alkoxide and the tetraalkoxysilane (including the vapor of the hydrophobic material in some cases), the It becomes possible to bring the titanium alkoxide and the tetraalkoxysilane into contact. By employing the method (i) and bringing the vapor of the titanium alkoxide and the tetraalkoxysilane into contact with the surface of the organic silica thin film, the hydroxyl groups on the surface of the organic silica thin film and the titanium alkoxide are and the hydrolysis reaction with the tetraalkoxysilane, thereby forming a layer containing titanium oxide (composite oxide layer of titania and silica, optionally further containing the hydrophobic material) on the surface of the organic silica thin film. It is also possible to form the layer containing the reactant more uniformly.

Further, after the titanium alkoxide and the tetraalkoxysilane (and the hydrophobic material, if necessary) are brought into contact with the surface of the organic silica thin film in this manner, the organic silica thin film is reacted with the organic It becomes possible to form a layer containing titanium oxide (a composite oxide layer of titania and silica) on the surface of the silica thin film. In this way, the titanium alkoxide and the tetraalkoxysilane are brought into contact with the surface of the organic silica thin film and then reacted to form a layer containing titanium oxide. It becomes possible to contain 0.5 to 4.0 atomic % of titanium oxide in the region up to 10 nm in terms of titanium element ratio. The method of contacting and reacting the titanium alkoxide and the tetraalkoxysilane (and the hydrophobic material, if necessary) on the surface of the organic silica thin film is not particularly limited. and a method in which the vapor of the tetraalkoxysilane is brought into contact with the surface of the organic silica thin film, then exposed to the atmosphere, and reacted with water vapor contained in the atmosphere to proceed with the hydrolysis reaction and the dehydration condensation reaction. is mentioned.

By forming the layer containing the titanium oxide in this way, it is possible to more efficiently form the titanium oxide in a region of up to 10 nm in the depth direction from the surface of the organic silica thin film in terms of the titanium element ratio. .5 to 4.0 at % can be contained.

In the second step, the layer containing the titanium oxide is formed, for example, on the surface of the organic silica thin film by hydrolysis reaction of hydroxyl groups on the surface of the organic silica thin film, the titanium alkoxide and the tetraalkoxysilane. In the case where the titanium oxide-containing layer is formed in advance, a layer (hydrophobic layer) made of the hydrophobic material is separately formed by applying a solution of the hydrophobic material on the surface of the layer containing the titanium oxide, thereby A hydrophobic group may be introduced onto the surface of the organic silica thin film.

As described above, the method (I) including the first step and the second step has been described as a method that can be suitably used for producing the organic silica substrate of the present invention. The method that can be preferably used for the purpose is not limited to the method (I). For example, as the step of forming the layer containing titanium oxide, a layer containing titanium oxide is formed in a liquid layer. A method of manufacturing an organic silica substrate by adopting a step of carrying out the above steps can also be used as appropriate.

The organic silica substrate for laser desorption/ionization mass spectrometry of the present invention has been described above. Hereinafter, the laser desorption/ionization mass spectrometry method of the present invention will be described.

[Laser desorption/ionization mass spectrometry]
The laser desorption/ionization mass spectrometry of the present invention is characterized in that the analysis substrate used in the laser desorption/ionization mass spectrometry is the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention. It is a way to

As a method for such laser desorption/ionization mass spectrometry, the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention (hereinafter, sometimes simply referred to as "the organic silica substrate of the present invention") is used as a substrate for analysis. (referred to as "") is not particularly limited, and a method of laser desorption/ionization mass spectrometry employing conditions similar to those employed in known methods can be employed.

Further, as a method of such laser desorption/ionization mass spectrometry, for example, the organic silica substrate of the present invention is used as an analysis substrate, and a sample containing molecules to be measured is supported on the surface of the organic silica substrate. After that, a method of desorbing/ionizing the molecules to be measured by irradiating the sample-carrying portion on the substrate with a laser beam and performing mass spectrometry can be adopted as a suitable method. A mass spectrometry method that can be suitably employed as the laser desorption/ionization mass spectrometry method of the present invention will be briefly described below.

A sample used in such a method contains molecules to be measured. Although such a molecule to be measured is not particularly limited, it is preferably a biologically-derived molecule or a molecule in a biological sample, since the present invention enables measurement with higher detection sensitivity. Sugars, proteins, peptides, glycoproteins, glycopeptides, nucleic acids, glycolipids and the like are more preferable as such molecules derived from a living organism or molecules in a biological sample, and the effects of the present invention can be obtained for these molecules. It tends to be possible to make it more advanced. In addition, such molecules to be measured include those prepared from natural products, those prepared by chemically or enzymatically partially modifying natural products, and those prepared chemically or enzymatically. can be anything. Moreover, it may have a partial structure of a molecule contained in a living body, or may be produced by imitating a molecule contained in a living body.

In addition, such a sample (sample containing the molecule to be measured) may be the molecule to be measured itself, or a sample containing the molecule to be measured (e.g., biological tissue, cell, body fluid, or secretion (e.g., , blood, serum, urine, semen, saliva, tears, sweat, feces, etc.). In this way, a biological sample may be directly used as the sample (sample containing molecules to be measured). After the precursor of the sample (precursor of the molecule to be measured, etc.) is supported on the surface of the organic silica substrate of the present invention, an enzyme treatment or the like is performed to prepare the molecule to be measured on the surface of the organic silica substrate. You may In this case, the sample precursor is supported on the organic silica substrate of the present invention and then treated, so that the sample is supported on the surface of the organic silica substrate.

In addition, the above-mentioned "molecules to be measured" may be molecules contained in the sample whose chemical structure is to be determined, or molecules contained in the sample. Alternatively, it may be a molecule obtained by derivatizing a molecule whose chemical structure is to be determined (for example, a molecule subjected to mass spectrometry obtained by binding a so-called labeled molecule to a molecule whose chemical structure is to be determined). Thus, the "measurement target molecule" may be a non-derivatized molecule or a molecule derivatized with a labeling molecule. The presence or absence of derivatization is not particularly limited, and may be appropriately determined according to the type of organic group of the organic silica thin film to be used, the type of molecule whose chemical structure is to be determined, and the like. Thus, derivatization may not be necessary depending on the molecule whose chemical structure is to be determined. Although the molecular weight of such a molecule to be measured is not particularly limited, it is preferably 160 or more because accurate measurement by other measuring methods is difficult and the characteristics of the present invention are more likely to be exhibited. , is more preferably 500 or more, and particularly preferably 1000 or more.

In addition, when a molecule obtained by derivatizing a molecule whose chemical structure is to be determined is used as the molecule to be measured, the derivatization is performed by receiving light energy absorbed by the organic group (light energy absorbed by the organic silica thin film). It is preferable to carry out covalent bonding with a labeling molecule that enables the absorption, preferably a labeling molecule having an absorption band that overlaps the emission spectrum of the organic silica thin film.

Such labeling molecules are not particularly limited as long as they have the effect of accepting energy provided from the organic silica thin film, but molecules commercially available as fluorescent labeling reagents may be used. Examples of such labeling molecules include pyrene derivatives, fluorescein derivatives, rhodamine derivatives, cyanine dyes, Alexa Fluor (registered trademark), 2-aminoacridone, 6-aminoquinoline and the like.

In addition, the combination of the organic silica thin film as the energy donor and the labeling molecule as the energy acceptor will affect the efficiency of energy transfer, the overlap between the emission spectrum of the organic silica thin film and the absorption spectrum of the molecule to be measured, and the strength of interaction. It can be determined appropriately from the points. For example, when a crosslinked organic silica thin film having a triphenylamine group is used as the organic silica thin film, 2-aminoacridone or the like can be suitably used as the labeling molecule, and a methylacridone group can be used as the organic silica thin film. When using a crosslinked organic silica thin film having - quinoxalinone and the like can be preferably used. Such a labeling molecule preferably has a functional group that easily chemically bonds with the target molecule. you can go

The reason why the molecules to be measured can be ionized more efficiently by using the organic silica substrate of the present invention as a substrate for analysis is not necessarily clear, but the present inventors speculate as follows. . That is, first, when the organic silica thin film included in the organic silica substrate of the present invention is irradiated with laser light, the laser light is absorbed by the organic groups in the film. By absorbing the laser light in this manner, the light energy absorbed by the organic silica thin film can be transferred to the molecule to be measured (energy acceptor). Thus, the organic silica thin film according to the present invention acts as an energy donor that transfers light energy to molecules to be measured (energy acceptors) when irradiated with laser light. As for the energy transfer from such an organic silica thin film (energy donor) to the molecule to be measured (energy acceptor), energy transfer not via light emission (for example, intermolecular excitation energy transfer, electron transfer, or thermal transfer as energy), and energy transfer via light emission (for example, energy transfer in which the molecule to be measured absorbs light emitted from an organic group of an organic silica thin film that has absorbed laser light (energy transfer due to reabsorption of light emission)) can be considered. The present inventors presume that such energy transfer enables more efficient desorption/ionization of molecules to be measured using laser light.

In addition, in the present invention, such energy transfer is thought to make it possible to more efficiently desorb/ionize the molecule to be measured using laser light. The organic groups are preferably selected so as to satisfy the following relationships. That is, regardless of the energy transfer (energy transfer from the organic silica thin film (energy donor) to the molecule to be measured (energy acceptor)), the energy can be transferred more efficiently. From the point of view, after the irradiation laser light is absorbed by the organic group in the organic silica thin film, the spectrum of light emitted from the organic group of the organic silica thin film (luminescence spectrum from the organic group) and the molecule to be measured It is more preferable to select the organic group and the molecule to be measured such that the absorption spectrum of the . Thus, when the emission spectrum from the organic group and the absorption spectrum of the molecule to be measured overlap at least one wavelength, the light energy absorbed by the organic silica thin film or the excitation of the organic silica thin film Energy tends to transfer more efficiently to the molecule being measured. In particular, when the energy is transferred via light emission, the organic silica thin film absorbs the irradiated laser light and emits light, and the emission spectrum of the organic silica thin film (the emission spectrum from the organic group) and the above More preferably, the absorption spectrum of the molecule to be measured overlaps at least one wavelength. This is because the light energy emitted from the organic silica thin film by such light emission tends to efficiently move to the molecule to be measured.

In addition, regardless of the form of energy transfer (whether via light emission or not), the short wavelength end of the emission spectrum of the above organic silica thin film is on the short wavelength side of the absorption spectrum of the molecule to be measured, so that the emission spectrum of the organic silica thin film and the absorption spectrum of the molecule to be measured overlap at least one wavelength. is more preferable. In such a case, the light energy absorbed by the organic silica thin film tends to move more efficiently to the molecule to be measured as light energy or excitation energy.

In such a laser desorption/ionization mass spectrometry method, a sample containing molecules to be measured is first supported on the surface of an organic silica substrate during mass spectrometry. The method for supporting such a sample is not particularly limited. It is preferable to adopt the method of supporting the sample on the organic silica substrate of the invention. The solvent used for the solution containing such a sample is not particularly limited. , acetonitrile, ethanol, acetone, and a mixed solvent of two or more thereof are preferably used. In addition, the method of applying the solution containing the sample is not particularly limited, but it can be suitably applied when it is necessary to handle an extremely small amount of a biological sample, etc., and the simplicity of the experimental operation is further enhanced. Therefore, it is preferable to employ a method of coating by dropping the solution. As described above, after the sample precursor (molecules before enzymatic treatment) is supported on the organic silica substrate of the present invention, enzymatic treatment is carried out to prepare molecules to be measured (enzyme-treated product) on the substrate. As a result, a sample containing molecules to be measured (enzyme-treated product) may be supported on the surface of the organic silica substrate of the present invention. In this way, a sample containing the molecule to be measured (the molecule itself to be measured, a derivative of the molecule to be measured, a mixture of the molecule to be measured and a standard substance, etc.) is finally supported on the organic silica substrate of the present invention. is possible, the method of supporting the sample is not particularly limited.

In the present invention, a sample containing molecules to be measured is supported on the surface of the organic silica substrate of the present invention as described above, and then the sample-supported portion of the film is irradiated with a laser beam to obtain the above-described A molecule to be measured is desorbed/ionized and subjected to mass spectrometry.

The laser light source used for such mass spectrometry is not particularly limited. A laser light source may be mentioned, but a nitrogen laser or a YAG laser triple wave laser light source is preferable from the viewpoint that the organic silica thin film can efficiently absorb light.

Also, the sample carrying portion on the organic silica substrate is irradiated with laser light using the laser light source (for example, nitrogen laser light source). By irradiating the sample carrying portion with the laser beam in this way, it is possible to desorb/ionize the molecules to be measured. As already explained, the mechanism of ionization is that the irradiated laser is absorbed by the organic group present at the laser irradiation site, and the absorbed light energy is efficiently transferred to the molecule to be measured. The inventors speculate. The irradiation conditions (irradiation intensity, irradiation time, etc.) of the laser beam are not particularly limited, and the optimum conditions may be appropriately selected from known mass spectrometry conditions according to the molecule to be measured. .

In addition, the method for separating and detecting ions for mass spectrometry is not particularly limited, and includes a double focusing method, a quadrupole focusing method (quadrupole (Q) filter method), a tandem quadrupole (QQ) method, an ion Trapping methods, time-of-flight (TOF) methods, etc. can be employed as appropriate, whereby ionized molecules can be separated and detected according to their mass/charge ratio (m/z). For such separation and detection of ions, a commercially available device can be used as appropriate. An analyzer (trade name “AXIMA-QIT, etc.”) or the like may be used as appropriate. In this manner, mass spectrometry of the ionized molecules to be measured can be performed.

Since the laser desorption/ionization mass spectrometry method of the present invention uses the organic silica substrate of the present invention as a substrate for analysis, it can be selected from various organic molecules and biomolecules. The target molecule can be detected with high sensitivity, and the sample containing the target molecule can be more uniformly adsorbed and supported on the substrate by the titanium oxide present on the surface and its vicinity. When performing analysis on multiple measurement points within the sample carrying area (within the analysis area) containing (A signal with a similar intensity can be measured at each measurement point), and the molecule to be measured can be detected with high reproducibility, so that mass spectrometry can be performed on the molecule to be measured with high reproducibility. Furthermore, since the laser desorption/ionization mass spectrometry method of the present invention uses the organic silica substrate of the present invention, the matrix compound ( Since it is not necessary to use low-molecular-weight organic substances), the peak derived from the target molecule can be measured with high sensitivity even in the molecular region where the signal derived from the matrix is detected without detecting the peak derived from the matrix. is also possible.

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
Formula (A) below:

[In the formula (A), the group represented by ⁱ Pr represents an isopropyl group. ]
The ratio of the mass of silicon to the mass of the organic group in the compound ([mass of silicon]/[mass of organic group]) represented by (75 mg): 0.174 [mass ratio of silicon is 17.4% by mass compound], and the term “organic group” as used herein refers to a residue obtained by removing two groups represented by —Si(O ⁱ Pr) ₃ from the above formula (A). A mixture was obtained by dissolving in 0 mL of 2-propanol. Next, 10 μL of 2M (mol/L) hydrochloric acid was added to the mixed solution and stirred at room temperature for 60 minutes (1 hour) to prepare a sol solution. Next, after filtering the obtained sol solution with a membrane filter to remove impurities, 50 μL of the filtered sol solution was dropped onto a 1 cm square silicon substrate (10 mm long and 10 mm wide), An organic silica thin film was formed on the silicon substrate by spin coating (rotation speed: 1500 rpm, duration: 10 seconds). In the film (organic silica thin film) obtained from the sol solution in this way, most (almost) of the solvent evaporated (volatilized) during the spin coating. Since most of the solvent is removed by evaporation during film formation, it was difficult to obtain an accurate film thickness of the coating film. It was confirmed that the film thickness was in the range of 200 to 350 nm. Thus, a laminate was obtained in which the organic silica thin film was laminated on the silicon substrate (base material).

Next, the obtained laminate and a small bottle containing 300 μL of 6 M (mol/L) hydrochloric acid were fixed to the bottom of a sealable container made of Teflon (registered trademark), and then the container was sealed. The organic silica thin film on the silicon substrate (substrate) was exposed to hydrochloric acid vapor in the container by heating at 80° C. for 3 hours. Such exposure to hydrochloric acid vapor makes it possible to further promote hydrolysis of the residual alkoxy groups and curing of the thin film, and to expose hydroxyl groups on the surface of the organic silica thin film. After the laminate (laminate laminated in the order of base material/organic silica thin film) after being exposed to the vapor of hydrochloric acid in this way is transferred to another sealable container made of Teflon (registered trademark), the gas is The atmosphere is an argon gas atmosphere, and tetramethoxysilane (a.k.a. Tetramethyl orthosilicate, abbreviated as “TMOS”: 150 μL) and tetraethoxytitanium (a.k.a. tetraethyl orthotitanate) are placed in the vicinity of the laminate in the container. (Tetraethyl orthotitanate), abbreviated as “TEOTi”: 50 μL), was fixed. Next, the sealable container is sealed under an argon gas atmosphere, and the surface of the organic silica thin film of the laminate is heated at 150° C. for 1 hour in the sealed container under an argon gas atmosphere. By forming a titanium oxide-containing layer (a layer consisting of a reactant of TMOS and TEOTi) on the top, a laser desorption/ionization mass spectrometer having an organic silica thin film in which titanium oxide is introduced near the surface is obtained. An organic silica substrate (a laminate in which an organic silica thin film having a titanium oxide introduced in the vicinity of the surface is laminated on a substrate) was obtained.

[Evaluation of properties of the organic silica substrate obtained in Example 1]
<Characteristics of the organic group of the organic silica thin film provided by the organic silica substrate>
In order to measure the absorption wavelength of the organic group in the organic silica thin film provided in the organic silica substrate obtained in Example 1, a measurement sample was formed as follows and the ultraviolet/visible absorption spectrum was measured. That is, first, a sol solution was prepared in the same manner as in Example 1, filtered through a membrane filter, and then the filtered sol solution was spin-coated on a quartz substrate (rotation speed: 1500 rpm, duration: 10 seconds). Thus, an organic silica thin film was formed, and this was used as a sample for measurement.

FIG. 4 shows the UV/visible absorption spectrum of a sample for such measurements. As is clear from the results of the ultraviolet/visible absorption spectrum of such a measurement sample (FIG. 4), the organic silica thin film (represented by the above formula (A)) included in the organic silica substrate obtained in Example 1 It was confirmed from the ultraviolet/visible absorption spectrum that the organic group in the compound (organosilicon compound polymer) has absorption maximum wavelengths of 243 nm, 344 nm, and 354 nm, and the organic silica thin film obtained in Example 1 It was confirmed that the organic groups inside were capable of absorbing laser light.

<XPS analysis of organic silica thin film provided on organic silica substrate>
Regarding the organic silica thin film provided in the organic silica substrate obtained in Example 1, components existing within a range of up to 10 nm in the depth direction from the surface of the thin film were detected by X-ray photoelectron spectroscopy (XPS). , by determining the content ratio (atomic %: at%) of titanium (Ti) with respect to the total amount of all measured elements (Si, Ti, C, N, O), 10 nm in the depth direction from the surface of the organic silica thin film The amount of titanium oxide present in the range of up to was determined. In addition, the content ratio of titanium (Ti) to the total amount of all measured elements (Si, Ti, C, N, O) is that the binding energy of the spectrum of Ti observed by XPS is an oxide as a chemical bonding state of titanium. , it was regarded as the content of titanium oxide. In the measurement, an XPS device (trade name “PHI 5000 Versaprobe II” manufactured by ULVAC-PHI) was used as a measurement device, and the following measurement conditions were adopted.
[Measurement conditions for X-ray photoelectron spectroscopy]
X-ray source: AlKα, 1486.6ev
Photoelectron extraction angle: 45°
Analysis region: 100 μm diameter region Pass energy: 93.8 eV
Energy step: 0.2 eV.

As a result of such XPS measurement, the organic silica thin film included in the organic silica substrate obtained in Example 1 contained 1.8 atomic % of titanium oxide in the range of 10 nm in the depth direction from the surface of the thin film. It was confirmed that

( Comparative Example 1 )
A treatment of heating at 150°C for 1 hour in an argon gas atmosphere in a sealed container when forming a layer containing titanium oxide on the surface of the organic silica thin film of the laminate after exposure to hydrochloric acid vapor Instead of applying, in a sealed container, in an argon gas atmosphere, heat treatment was performed at 150 ° C. for 2 hours, except that the heat treatment time when forming the layer containing titanium oxide was 1 hour to 2 hours. ) was prepared in the same manner as in Example 1, using an organic silica substrate for laser desorption/ionization mass spectrometry with an organic silica thin film in which titanium oxide was introduced in the vicinity of the surface (titanium oxide was introduced in the vicinity of the surface). Thus, a laminate was obtained in which the introduced organic silica thin film was laminated on the base material.

In addition, the same method as "XPS analysis of the organic silica thin film included in the organic silica substrate" performed when evaluating the characteristics of the organic silica substrate obtained in Example 1 was used. When the amount of titanium oxide existing in a range of 10 nm in the depth direction from the surface of the organic silica thin film provided on the organic silica substrate was measured, the amount of titanium oxide in the range of 10 nm in the depth direction from the surface of the thin film was was confirmed to contain 2.8 at %. Considering that the organic silica thin film formed in Comparative Example 1 was formed using the compound represented by the above formula (A), it was formed in the same manner as the organic silica thin film formed in Example 1. It is clear that the thin film has an organic group capable of absorbing laser light (the organic group in the thin film has absorption maximum wavelengths of 243 nm, 344 nm and 354 nm).

(Example 2 )
Using the organic silica substrate obtained in Example 1 as an analytical substrate for laser desorption/ionization mass spectrometry, laser desorption/ionization mass spectrometry (LDI-MS) was performed as follows. rice field.

That is, first, angiotensin I is selected as a molecule to be measured, and angiotensin I is added to a 0.1% by mass trifluoroacetic acid aqueous solution as a solvent (aqueous solution in which trifluoroacetic acid is dissolved in water at a concentration of 0.1% by mass). to obtain a solution (A) of angiotensin I with a concentration of 1.0 pmol/μL. Next, 1.0 μL of the solution (A) was applied onto the surface of the organic silica thin film of the organic silica substrate obtained in Example 1 by dropping. Next, the organic silica substrate coated with the solution (A) was air-dried to carry angiotensin I (sample) on the surface of the organic silica thin film of the substrate. Next, within the region carrying angiotensin I (where the solution was applied), arbitrarily selected 10 different regions (10 different circular regions with a diameter of 100 μm) were used as measurement points, and each measurement point Then, using a mass spectrometer (MALDI-TOF-MS device, trade name “Autoflex”) manufactured by Bruker Daltonics as an analysis device, each was irradiated with an N ₂ laser (wavelength: 337 nm), in reflectron mode. Mass spectrometry was performed. At the time of analysis, the _N2 laser was irradiated 10 times at a laser intensity of 30% for each measurement point (a total of 10 shots of the _N2 laser was irradiated at each measurement point), and the spectrum was integrated to obtain a mass. A spectrum was obtained.

As a result of such mass spectrometry, the graphs of the mass spectrum (LDI-MS spectrum) of angiotensin I (monoisotopic mass: 1295.6 Da) at any one measurement point are shown in FIGS. 5 and 6. shown. FIG. 7 shows the signal intensity of angiotensin I (monoisotopic mass: 1295.6 Da) at 10 different measurement points. 5 and 6 show the LDI-MS spectrum of the measurement point 8 in FIG. From the results shown in FIGS. 5 and 6, it can be seen that when the organic silica substrate obtained in Example 1 is used, angiotensin I can be converted to angiotensin I by laser desorption/ionization mass spectrometry (LDI-MS). It can be seen that the corresponding signal (m / z = 1296.2) can be clearly confirmed with the isotope pattern, and the results shown in FIG. 7 show that the same level of signal intensity can be confirmed at any measurement point. rice field.

( Comparative example 2 )
Ten arbitrarily selected different regions ( 10 measurement points) were subjected to mass spectrometry.

FIG. 8 shows the signal intensity of angiotensin I (monoisotopic mass: 1295.6 Da) at 10 different measurement points as a result of such mass spectrometry. From the results shown in FIG. 8, when the organic silica substrate obtained in Comparative Example 1 was used, laser desorption/ionization mass spectrometry (LDI-MS) showed similar signal intensities at any measurement point. I have found that it can be verified.

(Comparative Example 3 )
A sol solution similar to the filtered sol solution prepared in Example 1 was prepared, dropped onto a 1 cm square silicon substrate (10 mm long and 10 mm wide), and spin-coated under the same conditions as in Example 1. (Rotation speed: 1500 rpm, duration: 10 seconds) to form an organic silica thin film on a silicon substrate (base material), and the resulting laminate (an organic silica thin film is laminated on a silicon substrate (base material). The laminate obtained by the method used in Example 1 was used as an organic silica substrate for laser desorption/ionization mass spectrometry for comparison. was used as an organic silica substrate for laser desorption/ionization mass spectrometry for comparison).

(Comparative Example 4 )
After obtaining a laminate in the same manner as in Comparative Example 3 , the laminate and a small bottle containing 300 μL of 6 M (mol / L) hydrochloric acid are sealed with Teflon (registered trademark). After fixing to the bottom of each container, the container is sealed and heated at 80 ° C. for 3 hours to expose the organic silica thin film on the silicon substrate (base material) to the vapor of hydrochloric acid in the container, For comparison, an organic silica substrate for laser desorption/ionization mass spectrometry was obtained, which consisted of a laminate in which an organic silica thin film was laminated on a silicon substrate (base material).

(Comparative Examples 5-6 )
The procedure of Example 2 was repeated except that instead of using the organic silica substrate obtained in Example 1, the organic silica substrate obtained in Comparative Example 3 and the organic silica substrate obtained in Comparative Example 4 were used . Then, mass spectrometry was performed on 10 different arbitrarily selected regions (10 measurement points).

As a result of laser desorption/ionization mass spectrometry (LDI-MS) for such 10 measurement points, angiotensin at each measurement point when using the organic silica substrate obtained in Comparative Example 3 (Comparative Example 5 ) A graph showing the signal intensity of I (monoisotopic mass: 1295.6 Da) is shown in FIG. A graph showing the signal intensity of angiotensin I (Monoisotopic mass: 1295.6 Da) of . From the results shown in FIGS. 9 and 10, when the organic silica substrates obtained in Comparative Examples 3 and 4 were used, laser desorption/ionization mass spectrometry (LDI-MS) was performed. And when compared with the case of using the organic silica substrate obtained in Comparative Example 1 , it was found that the variation in signal intensity at each measurement point was not always sufficient.

[Results of mass spectrometry using the organic silica substrates obtained in Example 1 , Comparative Example 1 and Comparative Examples 3 and 4 (results of mass spectrometry of Example 2, Comparative Example 2 and Comparative Examples 5 and 6 )]
Results of mass spectrometry using the organic silica substrates obtained in Example 1 , Comparative Example 1 , and Comparative Examples 3 and 4 (10 different arbitrarily selected regions (10 measurement points) of mass spectrometry From the results (FIGS. 7-10)) (from the mass spectrometry results of Example 2, Comparative Example 2 and Comparative Examples 5-6) , angiotensin I (mono Table 1 shows the average value of the signal intensity of the isotopic mass (Monoisotopic mass: 1295.6 Da) and its standard deviation.

As is clear from the results shown in Table 1, the organic silica substrates obtained in Example 1 and Comparative Example 1, which have an organic silica thin film containing a predetermined amount of titanium oxide in a range of 10 nm in the depth direction from the surface, were used. When used, compared with the case of using the organic silica substrate obtained in Comparative Examples 3 and 4 (no titanium oxide was introduced into the organic silica thin film provided on the substrate), 10 measurement points When laser desorption / ionization mass spectrometry (LDI-MS) is performed for It was found that higher sensitivity measurement is possible when using an organic silica substrate. Further, as is clear from the results shown in Table 1, when the organic silica substrates obtained in Example 1 and Comparative Example 1 were used, the organic silica substrates obtained in Comparative Examples 3 and 4 were used. In contrast to the case, when laser desorption/ionization mass spectrometry (LDI-MS) is performed for 10 measurement points, the standard deviation of the signal intensity of the mass spectrum obtained is found to be a small value. rice field. From the results shown in Table 1 and the results shown in FIGS. It was found that when the obtained organic silica substrate was used, the variation in signal intensity at each measurement point was further suppressed, and the uniformity of the signal intensity of the obtained mass spectrum was improved.

From these results, Example 1 comprising an organic silica thin film containing a predetermined amount of titanium oxide in a range of 10 nm in the depth direction from the surface as a substrate for laser desorption/ionization mass spectrometry (LDI-MS) analysis. And when the organic silica substrate obtained in Comparative Example 1 is used, when measurements are performed at a plurality of measurement points under the same conditions, the uniformity of the signal intensity of the mass spectrum at each measurement point becomes higher, and the It was found that mass spectrometry with high reproducibility can be performed.

(Example 3 )
Tetramethoxysilane (TMOS: 150 μL) and tetraethoxytitanium (TEOTi: 50 μL) were added when forming a layer containing titanium oxide on the surface of the organic silica thin film of the laminate after exposure to hydrochloric acid vapor. Tetramethoxysilane (TMOS: 150 μL), Tetrapropyl orthotitanate (TPOTi: 50 μL), and trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane as a hydrophobic material instead of using a small vial. In the same manner as in Example 1, except that a vial containing (Trimethoxy (1H, 1H, 2H, 2H-nonafluorohexyl) silane: long-chain fluoroalkylsilane (FAS-9): 25 μL) was used. An organic silica substrate for laser desorption/ionization mass spectrometry (a laminate in which an organic silica thin film with titanium oxide introduced near the surface is laminated on a substrate) comprising an organic silica thin film with titanium oxide introduced. Obtained.

In addition, the same method as "XPS analysis of the organic silica thin film included in the organic silica substrate" performed when evaluating the characteristics of the organic silica substrate obtained in Example 1 was used. When the amount of titanium oxide existing in a range of 10 nm in the depth direction from the surface of the organic silica thin film provided on the organic silica substrate was measured, the amount of titanium oxide in the range of 10 nm in the depth direction from the surface of the thin film was was confirmed to be contained at 1.1 at %. Considering that the organic silica thin film formed in Example 3 was formed using the compound represented by the above formula (A), the organic silica thin film formed in Example 1 was It is clear that the thin film has an organic group capable of absorbing laser light (the organic group in the thin film has absorption maximum wavelengths of 243 nm, 344 nm and 354 nm). In addition, since a hydrophobic material (trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane) is used when forming the layer containing titanium oxide, the organic silica formed in Example 3 It is clear that 1H,1H,2H,2H-nonafluorohexyl groups (hydrophobic groups) are introduced into the surface of the thin film from such a hydrophobic material.

(Example 4 )
10 arbitrarily selected different regions ( 10 measurement points) were subjected to mass spectrometry.

As a result of such mass spectrometry, the graphs of the mass spectrum (LDI-MS spectrum) of angiotensin I (monoisotopic mass: 1295.6 Da) at any one measurement point are shown in FIGS. 11 and 12. , and the signal intensity of angiotensin I (monoisotopic mass: 1295.6 Da) at 10 different measurement points is shown in FIG. From the results shown in FIGS. 11 and 12, when the organic silica substrate obtained in Example 3 is used, it corresponds to Angiotensin I by laser desorption/ionization mass spectrometry (LDI-MS). It was found that the signal (m/z=1296.2) was clearly identifiable with the isotope pattern. Thus, from the results shown in FIGS. 11 and 12, it was found that the use of the organic silica substrate obtained in Example 3 enables measurement with sufficiently high sensitivity. Further, from the results shown in FIG. 13, when the organic silica substrate obtained in Example 3 was used, laser desorption/ionization mass spectrometry (LDI-MS) determined any position of 10 different measurement points. It was found that the same level of signal intensity could be confirmed even in From the results of laser desorption/ionization mass spectrometry (LDI-MS) using the organic silica substrate obtained in Example 3 , the average value of the signal intensity at 10 different measurement points and its standard deviation were obtained. , the average signal intensity was 2408.9 and the standard deviation of the signal intensity was 69.3. From these results and the measurement results of Comparative Examples 5 and 6 (see Table 1), it can be concluded that when the organic silica substrate obtained in Example 3 is used for laser desorption/ionization mass spectrometry (LDI-MS), measurement It was found that the variation in signal intensity from point to point was further suppressed, the uniformity of the signal intensity of the mass spectrum was higher at each measurement point, and it was possible to perform mass spectrometry with higher reproducibility.

(Example 5 )
Instead of using an angiotensin I solution (A) with a concentration of 1.0 pmol/μL, polyethylene glycol dimethyl ether (abbreviated as “PEGDME”) with an average molecular weight of about 1000 g/mol was added to 0.1% by mass of trifluoro Using a polyethylene glycol dimethyl ether solution (B) with a concentration of 1.0 pmol/μL obtained by dissolving in an aqueous acetic acid solution, instead of measuring 10 arbitrarily selected measurement points, any 1 Mass spectrometry was performed on an arbitrary measurement point in the region supporting PEGDME (the location where the solution was applied) in the same manner as in Example 4 , except that the measurement was performed on the point measurement point.

As a result of such mass spectrometry, FIG. 14 shows a graph of a mass spectrum (LDI-MS spectrum) of polyethylene glycol dimethyl ether (average molecular weight: about 1000 g/mol) at one arbitrary measurement point. As is clear from the results shown in FIG. 14, a polyethylene glycol dimethyl ether signal (m/z=1081.2) was clearly confirmed in the obtained mass spectrum. From these results, it was found that when the organic silica substrate obtained in Example 3 was used for laser desorption/ionization mass spectrometry (LDI-MS) (Example 5 ), it was sufficiently high for polyethylene glycol dimethyl ether. It turned out that it is possible to perform a sensitive analysis.

(Example 6 )
Instead of using the solution (A) of angiotensin I with a concentration of 1.0 pmol / μL, Substance P (Substance P: P substance) was dissolved in an aqueous solution of 0.1% by mass of trifluoroacetic acid, and the concentration was 1 Mass spectrometry was performed on 10 arbitrarily selected different regions (10 measurement points) in the same manner as in Example 4 , except that the solution (C) of .0 pmol / μL of substance P was used. gone.

As a result of such mass spectrometry, the graph of the mass spectrum (LDI-MS spectrum) of substance P (monoisotopic mass: 1346.7 Da) at any one measurement point is shown in FIGS. 15 and 16. show. As is clear from the results shown in FIGS. 15 and 16, the substance P signal (m/z=1347.0) was clearly confirmed with the isotope pattern in the obtained mass spectrum. From these results, when the organic silica substrate obtained in Example 3 is used for laser desorption/ionization mass spectrometry (LDI-MS) (Example 6 ), it is sufficiently high for substance P. It turned out that it is possible to perform a sensitive analysis. In such mass spectrometry (Example 6 ), the signal intensities of the mass spectra at 10 different measurement points were approximately the same, the average value of the signal intensities was 2315.6, and the signal intensity was 116.5, it was found that the uniformity of the signal intensity of the mass spectrum at each measurement point was sufficiently high, and mass spectrometry with sufficiently high reproducibility could be performed.

(Example 7 )
The compound represented by formula (A) (180 mg) was dissolved in 2.0 mL of 1-propanol to obtain a mixed solution. Next, 24 μL of 2M (mol/L) hydrochloric acid was added to the mixed solution and stirred at room temperature for 60 minutes (1 hour) to prepare a sol solution. Next, after filtering the obtained sol solution with a membrane filter to remove impurities, the filtered sol solution was dropped onto a 2 cm square silicon substrate (20 mm long and 20 mm wide) and spun. By coating (rotation speed: 1400 rpm, duration: 4 seconds), an organic silica thin film (thickness: in the range of 200 to 350 nm) was formed on the silicon substrate. Next, immediately after forming a thin film on the silicon substrate by spin coating as described above, a nanomold made of polyethylene terephthalate (trade name “FleFimo” manufactured by Soken Chemical, nanopillar array, pitch 250 nm, pillar diameter 150 nm, pillar height (thickness 250 nm) was quickly placed on the surface of the thin film and pressed for 2 hours under the condition of 1.4 tons using a plate press. After that, the nanomold was removed to obtain a laminate in which an organic silica thin film having a concavo-convex structure was laminated on the substrate.

Next, the obtained laminate and a small bottle containing 300 μL of 6 M (mol/L) hydrochloric acid were fixed to the bottom of a sealable container made of Teflon (registered trademark), and then the container was sealed. Then, the organic silica thin film having the uneven structure on the silicon substrate (base material) was exposed to the vapor of hydrochloric acid in the container by heating at 80° C. for 3 hours. Such exposure to hydrochloric acid vapor makes it possible to further promote hydrolysis of residual alkoxy groups and curing of the thin film, and to expose hydroxyl groups on the surface of the organic silica thin film. In this way, a laminate (laminate in which substrate/organic silica thin film having uneven structure was laminated in this order) after exposure to hydrochloric acid vapor was obtained. After being exposed to the vapor of hydrochloric acid in this way, the laminate (laminate in which the base material/the organic silica thin film having the concave-convex structure was laminated in this order) was transferred to another sealable container made of Teflon (registered trademark). Then, the gas atmosphere is changed to an argon gas atmosphere, and tetramethoxysilane (TMOS: 150 μL), tetrapropoxytitanium (TPOTi: 50 μL), and trimethoxy (1H) as a hydrophobic material are placed in the vicinity of the laminate in the container. , 1H,2H,2H-nonafluorohexyl)silane (25 μL) each was secured. Next, the sealable container is sealed under an argon gas atmosphere, and the surface of the organic silica thin film of the laminate is heated at 150° C. for 1 hour in the sealed container under an argon gas atmosphere. A laser equipped with an organic silica thin film having an uneven structure in which titanium oxide is introduced near the surface by forming a layer containing titanium oxide (a layer consisting of TMOS, TEOTi and a reaction product of a hydrophobic material) on the top An organic silica substrate for desorption/ionization mass spectrometry (a laminate in which an organic silica thin film having an uneven structure with titanium oxide introduced near the surface is laminated on the substrate) was obtained.

As is clear from the method of manufacturing the substrate employed in Example 7 , basically the same as in Example 3 was used, except that a laminate in which organic silica thin films having an uneven structure were laminated was used. Since the titanium oxide was introduced in the vicinity of the surface of the organic silica thin film under the same conditions as those employed, in the obtained organic silica substrate (Example 7 ), the It is clear that the amount of titanium oxide present in the region up to 10 nm in the vertical direction is approximately the same as that of the organic silica substrate obtained in Example 3 . Considering that the organic silica thin film formed in Example 7 was formed using the compound represented by the above formula (A), the organic silica thin film formed in Example 1 was It is clear that the thin film has an organic group capable of absorbing laser light (the organic group in the thin film has absorption maximum wavelengths of 243 nm, 344 nm and 354 nm). In addition, since a hydrophobic material (trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane) is used when forming the layer containing titanium oxide, the organic silica formed in Example 7 It is clear that 1H,1H,2H,2H-nonafluorohexyl groups (hydrophobic groups) are introduced into the surface of the thin film from such a hydrophobic material.

[Regarding the uneven structure of the surface of the organic silica thin film prepared in Example 7 ]
<Microscopic measurement of an organic silica thin film having an uneven structure>
At the time of manufacturing the organic silica thin film having an uneven structure (porous organic silica thin film) as described above, the organic silica thin film having an uneven structure after removing the nanomold (before exposure to 6 mol/L hydrochloric acid vapor) The surface morphology of the thin films) was measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). As the scanning electron microscope (SEM), a scanning electron microscope manufactured by Hitachi High-Technologies Corporation (trade name "SU3500") was used, and as the atomic force microscope, a scanning probe microscope (SPM /AFM: A product name "NanoNavi E-sweep" manufactured by Hitachi High-Tech Science Co., Ltd.) was used.

As a result of such measurements, a scanning electron microscope (SEM) photograph of the surface of the organic silica thin film prepared in Example 7 is shown in FIG. As is clear from the SEM image shown in FIG. 17, the organic silica thin film prepared in Example 7 has a regular nanoporous structure (pore structure) in which the structure of the nanomold is transferred. I found out.

In addition, when measuring with an atomic force microscope (AFM), the measurement was performed at a plurality of locations by changing the measurement location, and a cross-sectional view (longitudinal cross-sectional view) was obtained at each measurement location. Then, from a plurality of cross-sectional views obtained by such AFM measurement, when the axial direction (long axis direction of the pore) of the uneven structure at arbitrary 100 points was measured, the axial direction of the measured uneven structure Also, the angle is within the range of 90°±30° with respect to the surface of the organic silica thin film opposite to the surface on which the uneven structure is formed, and the axial direction of the uneven structure is the direction of the organic silica thin film. It was confirmed that they were oriented substantially perpendicularly to the surface opposite to the surface on which the uneven structure was formed. In addition, from the cross-sectional view obtained by such AFM measurement, for each convex portion of arbitrary 100 points, the distance between the nearest convex portion at a position half the average height described later and the nearest convex portion By measuring the distance between the wall surfaces (horizontal distance) of the organic silica thin film and calculating the average value, the average value of the distance between the wall surfaces of the convex portions (average pore diameter of the pores) was measured. It was confirmed that the average value of the distance between the wall surfaces of the projections (average pore diameter of pores) was 140 nm. In addition, when the average height of the protrusions (average depth of the pores (recesses)) was obtained for the uneven structure at arbitrary 100 points from the cross-sectional view obtained by AFM measurement of the organic silica thin film, the height of the protrusions was It was found that the average value of (depth of recesses) was 200 nm. In addition, for any 100 or more convex portions, the horizontal distance between the vertices of the convex portion and the nearest convex portion was measured, and the average pitch of the concave and convex portions was obtained. The average pitch of the unevenness was 260 nm. Furthermore, the roughness factor of the surface of the organic silica thin film is measured by calculating the increase in the surface area due to the provision of the uneven structure, and using this value to calculate the ratio of the surface area of the uneven surface to the smooth surface. As a result, the roughness factor of the uneven structure on the thin film surface was 2.5.

(Example 8 )
The procedure of Example 2 was repeated except that instead of using the organic silica substrate obtained in Example 1 , the organic silica substrate obtained in Example 7 (a substrate provided with an organic silica thin film having an uneven structure) was used. Then, mass spectrometry was performed on 10 different arbitrarily selected regions (10 measurement points).

As a result of such mass spectrometry, graphs of the mass spectrum (LDI-MS spectrum) of angiotensin I (monoisotopic mass: 1295.6 Da) at any one measurement point are shown in FIGS. 18 and 19. shown in As is clear from the results shown in FIGS. 18 and 19, in the obtained mass spectrum, a signal (m/z=1296.2) corresponding to Angiotensin I is clearly accompanied by an isotope pattern. It was confirmed that it was possible to perform sufficiently sensitive analysis. In such mass spectrometry (Example 8 ), the signal intensities of the mass spectra at 10 different measurement points were approximately the same, the average value of the signal intensities was 976.1, and the signal intensity The standard deviation of was 276.2.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to detect a signal of a molecule to be measured with sufficiently high sensitivity without using a matrix compound during mass spectrometry, and a sample containing a molecule to be measured can be detected. When mass spectrometry is performed on a plurality of measurement points within the attached region, the uniformity of the signal intensity of the resulting mass spectrum can be made higher, and the reproducibility is higher at each measurement point. It is possible to provide an organic silica substrate for laser desorption/ionization mass spectrometry that enables mass spectrometry, and a laser desorption/ionization mass spectrometry method using the same. Therefore, the organic silica substrate for laser desorption/ionization mass spectrometry of the present invention is particularly useful as an analytical substrate for use in laser desorption/ionization (LDI).

10... conventional organic silica thin film containing no titanium oxide, 11... solution of sample (sample) containing molecules to be measured, S... sample, V... region where sample is not supported, 101... organic silica thin film, _{S1 . _} Major axis of spatial shape of pores (columnar shape of voids) of organic silica thin film, α: Angle formed by plane _S2 and major axis C of spatial shape of pores, T: Organic silica thin film having uneven structure thickness.

Claims (5)

An organic silica thin film made of organic silica having an organic group capable of absorbing laser light as a skeleton, wherein the organic group capable of absorbing laser light has a maximum absorption wavelength in a wavelength range of 200 to 1200 nm, and the organic A silica thin film for laser desorption/ionization mass spectrometry, characterized in that titanium oxide is contained in a region within a range of 10 nm in the depth direction from the surface of the silica thin film in an amount of 1.0 to 2.0 at% in terms of titanium element ratio. organic silica substrate. 2. The organic silica substrate for laser desorption/ionization mass spectrometry according to claim 1, wherein said organic group capable of absorbing laser light has a maximum absorption wavelength in the wavelength range of 200 to 600 nm. 3. The organic silica substrate for laser desorption/ionization mass spectrometry according to claim 1, wherein said organic silica thin film has an uneven structure with a roughness factor of 1.4 or more on its surface. 4. The organic silica substrate for laser desorption/ionization mass spectrometry according to claim 1, wherein said organic silica thin film has hydrophobic groups on its surface. A laser characterized in that the substrate for analysis used in laser desorption/ionization mass spectrometry is the organic silica substrate for laser desorption/ionization mass spectrometry according to any one of claims 1 to 4. Desorption/ionization mass spectrometry.

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