Modified base material, method for producing modified base material, and method for evaluating overlap density in modified base material

Abstract

To provide a modified base material whose entire surface is chemically modified with a polymer, and to which an overlap density is associated.SOLUTION: A modified base material comprises a base material and a polymer chemically modifying the entire surface of the base material. An overlap density, calculated on the basis of an average interval between adjacent polymers on the entire surface, the average interval corresponding to the surface area of the entire surface and the number of polymers chemically modified on the entire surface, and an inertia radius of the polymer chemically modifying the entire surface, is associated with the modified base material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to a modified substrate, the entire surface of which is chemically modified with a hydrophilic polymer, and also to a method for producing such a modified substrate, and a method for evaluating the overlap density of adjacent polymer chains in such a modified substrate. [Background technology]

[0002] Patent Document 1 describes a technique for using nanodiamond (ND) particles that contain an NV (Nitrogen-Vacancy) center inside and have a surface chemically modified with a shielding group as a fluorescent molecular probe. Such ND particles containing an NV center can be used not only as a fluorescent molecular probe, but also as a quantum sensor that senses temperature, pH, electric field, magnetic field, etc. in the environment in which the ND particles exist, and can also be used as a carrier that carries drugs in a drug delivery system.

[0003] Incidentally, ND particles that have not been chemically modified on the surface form clusters and adsorb organic matter such as proteins (see Non-Patent Document 1). Therefore, when ND particles that have not been chemically modified on the surface are injected into a living body (for example, into a blood vessel), proteins present in the living body aggregate on the surface of the ND particles or ND particle clusters. In order to avoid such clustering of ND particles and aggregation of proteins, chemical modification of ND particles is an important technique. For example, Non-Patent Document 2 describes a technique that uses poly(ethylene glycol) monomethyl ether (mPEG) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as shielding groups.

[0004] Furthermore, the effect of suppressing protein adsorption by using poly(ethylene glycol) (PEG) as a shielding group has been reported using a PEG-modified substrate (see Non-Patent Document 3). In the PEG-modified substrate used here, the surface composed of a metal oxide is chemically modified with PEG. In Non-Patent Document 3, the average distance between adjacent PEGs on the surface of this substrate is defined as L, and the radius of gyration defined as the root mean square of the distance from the center of gravity to each monomer unit when each PEG modifying the substrate is considered as a sphere is defined as R. g As L / 2R g The overlap density defined as: is used as an index for evaluating the protein adsorption inhibitory effect. The average spacing L is calculated from the surface area of ​​the chemically modified region on the substrate for which the protein adsorption inhibitory effect is to be evaluated, and the number of PEGs bound to that region. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2014 / 058012 [Non-patent literature]

[0006] [Non-Patent Document 1] Polyglycerol Grafting Shields Nanoparticles from Protein Corona Formation to Avoid Macrophage Uptake. ACS Nano 2020, 14 (6), 7216-7226. https: / / doi.org / 10.1021 / acsnano.0c02289. [Non-Patent Document 2] Zhang, X.; Fu, C.; Feng, L.; Ji, Y.; Tao, L.; Huang, Q.; Li, S.; Wei, Y. PEGylation and PolyPEGylation of Nanodiamond. Polymer (Guildf) 2012, 53 (15), 3178-3184. [Non-Patent Document 3] Kenausis, GL, Voeroes, J., Elbert,DL, Huang,N., Hofer,R., Ruiz-Taylor, L., Textor, M., Hubbell, JA, Spencer, ND, Poly(L-lysine)-g-Poly(ethylene glycol) Layers on Metal Oxide Surfaces: Attachment Mechanism and Effects of Polymer Architecture on Resistance to Protein Adsorption J. Phys. Chem. B 2000, 104, 3298-3309. Summary of the Invention [Problem to be solved by the invention]

[0007] Since it is necessary to evaluate the protein adsorption inhibitory effect even in ND particles whose entire surface is chemically modified, the inventors considered using the above-mentioned overlapping density as an index. As described above, to calculate the overlapping density, the surface area of ​​the chemically modified region, that is, in the case of ND particles, the surface area of ​​the entire surface of the ND particles is used.

[0008] Here, a method for calculating the surface area of ​​the entire surface of an ND particle can be considered to be a method in which the shape of the ND particle is considered to be spherical, and the surface area of ​​the ND particle considered to be spherical is calculated using the particle size of the ND particle obtained by a dynamic light scattering method. However, when the inventors observed the shape of the ND particle using an electron microscope, it was found that the shape significantly deviated from a spherical shape. Therefore, it was found that even if the average interval L was calculated using the surface area of ​​the ND particle obtained using this method and the overlapping density was further calculated, an accurate overlapping density could not be obtained. Due to this background, the overlapping density was not calculated for ND particles whose entire surface was chemically modified, even though it is an important index that determines the protein adsorption inhibitory effect.

[0009] One aspect of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a modified substrate having an associated overlap density, in which the entire surface of the modified substrate is chemically modified with a polymer. [Means for solving the problem]

[0010] A modified substrate according to a first aspect of the present invention is a modified substrate comprising a substrate and a polymer that chemically modifies the entire surface of the substrate, and an overlap density is associated with the modified substrate, the overlap density being calculated based on: (1) an average spacing between adjacent polymers on the entire surface, the average spacing depending on the surface area of ​​the entire surface and the number of polymers chemically modifying the entire surface; and (2) a radius of gyration of the polymer that chemically modifies the entire surface.

[0011] According to the above configuration, the modified substrate is a modified substrate in which the entire surface is chemically modified with a polymer and is associated with an overlap density, so that a user can use the overlap density as an index for evaluating, for example, the protein adsorption suppression effect of the modified substrate.

[0012] Furthermore, in the modified substrate according to the second aspect of the present invention, in addition to the configuration of the modified substrate according to the first aspect described above, the modified substrate is further associated with the radius of gyration.

[0013] According to the above configuration, the modified substrate is associated with a radius of gyration in addition to the overlap density, which allows the user to select a modified substrate using the radius of gyration as an index, thereby enabling the user to accurately select a modified substrate according to the application.

[0014] In addition, in the modified substrate according to the third aspect of the present invention, in addition to the configuration of the modified substrate according to the first or second aspect described above, the substrate is composed of a wide-gap semiconductor including a color center.

[0015] The modified substrate constructed as described above is suitable as a quantum sensor for acquiring biological information.

[0016] Furthermore, in the modified base material according to the fourth aspect of the present invention, in addition to the configuration of the modified base material according to any one of the first to third aspects described above, the base material is a particle having an average diameter of 400 μm or less.

[0017] Currently, particles having an average diameter of 400 μm or less are widely available on the market, and therefore, according to the above-mentioned configuration, commercially available particles can be used as the modified substrate.

[0018] Furthermore, in the modified substrate according to a fifth aspect of the present invention, in addition to the configuration of the modified substrate according to the fourth aspect described above, the substrate is a particle having an average diameter of 3 nm or more and 500 nm or less.

[0019] The modified substrate configured as described above can be applied to sites having fine structures such as capillaries, and is therefore suitable as a quantum sensor for acquiring biological information or a carrier for transporting drugs in a drug delivery system.

[0020] The modified base material according to the sixth aspect of the present invention has the same configuration as the modified base material according to any one of the first to fifth aspects described above, and further has a configuration in which the polymer is a hydrophilic polymer.

[0021] According to the above configuration, when the modified base material is injected into a living body, the affinity of the modified base material to the living body can be increased.

[0022] Furthermore, in the modified substrate according to the seventh aspect of the present invention, in addition to the configuration of the modified substrate according to any one of the first to sixth aspects described above, the polymer is a biocompatible polymer.

[0023] The modified substrate having the above-mentioned structure is modified with a biocompatible polymer, and therefore when the modified substrate is injected into a living body, it is possible to prevent adsorption or aggregation of physiological substances such as proteins, making the modified substrate suitable as a biomaterial.

[0024] Furthermore, in the modified base material according to an eighth aspect of the present invention, in addition to the configuration of the modified base material according to any one of the first to seventh aspects described above, the polymer is polyethylene glycol or polyglycerol.

[0025] Thus, examples of polymers include polyethylene glycol and polyglycerol, which are also examples of biocompatible polymers that have hydrophilic properties.

[0026] In addition, the modified substrate according to a ninth aspect of the present invention has, in addition to the configuration of the modified substrate according to any one of the first to eighth aspects described above, a configuration in which the overlap density is 1 or less.

[0027] The modified substrate having the above-described structure is suitable as a biomaterial because the entire surface of the modified substrate is modified with a polymer without leaving any gaps, and therefore adsorption or aggregation of physiological substances such as proteins can be prevented.

[0028] Furthermore, in the modified substrate according to aspect 10 of the present invention, in addition to the configuration of the modified substrate according to any one of the first to ninth aspects described above, a configuration is adopted in which the shape of the modified substrate is different from a figure.

[0029] When the shape of the modified substrate is different from a figure, the surface area of ​​the entire surface cannot be calculated based on the shape of the modified substrate. Therefore, in order to obtain the surface area, it is preferable to obtain the surface area using a gas adsorption method, as in the surface area acquisition step included in the method for producing a modified substrate and the method for evaluating the overlapping density in a modified substrate according to one embodiment of the present invention. Therefore, according to one embodiment of the present invention, even when the shape of the modified substrate is different from a figure, the overlapping density can be associated with the modified substrate, and further, the overlapping density can be used as an index for evaluating the protein adsorption inhibitory effect of the modified substrate.

[0030] Furthermore, a method for producing a modified substrate according to an eleventh aspect of the present invention is a method for producing a modified substrate comprising a substrate and a polymer chemically modifying an entire surface of the substrate, the method including: a surface area acquisition step of obtaining a total surface area of ​​the entire surface of the modified substrate, the entire surface of which has been chemically modified with the polymer, using a gas adsorption method; an average spacing calculation step of calculating an average spacing between adjacent polymers on the entire surface, the average spacing being based on the total surface area and the number of polymers chemically modifying the entire surface; and an overlapping density calculation step of calculating an overlapping density based on the average spacing and the radius of gyration of the polymer chemically modifying the entire surface.

[0031] The method for producing a modified substrate configured in this manner has the same effects as the modified substrate according to the first aspect described above.

[0032] Furthermore, in the surface area acquisition step of this production method, since the surface area of ​​the entire surface is obtained using a gas adsorption method, the surface area can be obtained even when the shape of the modified base material is different from the figure. Therefore, according to the above configuration, even when the shape of the modified base material is different from the figure, the overlapping density can be associated with the modified base material, and further, the overlapping density can be used as an index for evaluating the protein adsorption inhibitory effect of the modified base material.

[0033] In addition, in the method for producing a modified substrate according to aspect 12 of the present invention, in addition to the method for producing a modified substrate according to the above-mentioned eleventh aspect, a configuration is adopted which further includes an association step performed after the overlap density calculation step, in which the overlap density is associated with the modified substrate.

[0034] According to the above configuration, since the overlap density is associated with the corresponding modified base material, the overlap density associated with the modified base material can be presented to the user by any method, and therefore the overlap density can be used as an index for evaluating the protein adsorption inhibitory effect of the modified base material.

[0035] Furthermore, a method for producing a modified substrate according to a twelfth aspect of the present invention employs, in addition to the method for producing a modified substrate according to any one of the above-mentioned tenth or eleventh aspects, a configuration further including a chemical modification step carried out before the surface area acquisition step, in which the entire surface is chemically modified with a polymer.

[0036] As configured above, the method for producing a modified substrate according to one aspect of the present invention may further include a chemical modification step.

[0037] Furthermore, a method for evaluating a modified substrate according to a fourteenth aspect of the present invention is a method for evaluating an overlap density in a modified substrate comprising a substrate and a polymer chemically modifying an entire surface of the substrate, the method including: a surface area acquisition step of obtaining a total surface area of ​​the entire surface of the modified substrate, the entire surface of which has been chemically modified with the polymer, using a gas adsorption method; an average spacing calculation step of calculating an average spacing between adjacent polymers on the entire surface, the average spacing being based on the total surface area and the number of polymers chemically modifying the entire surface; and an overlap density calculation step of calculating an overlap density based on the average spacing and the radius of gyration of the polymer chemically modifying the entire surface.

[0038] The method for evaluating overlap density in a modified substrate configured in this manner has the same effects as the modified substrate according to the first aspect described above, and also has the same secondary effects as the method for producing a modified substrate according to the eleventh aspect described above. Effect of the Invention

[0039] According to one aspect of the present invention, in a modified substrate whose entire surface has been chemically modified with a polymer, the overlapping density can be used as an index for evaluating the protein adsorption inhibitory effect of the modified substrate. [Brief description of the drawings]

[0040] [Figure 1]1A and 1B are conceptual diagrams of a modified substrate according to a first embodiment of the present invention, in which (a) is a conceptual diagram showing a modified substrate having a particle-shaped substrate, and (b) is a conceptual diagram showing a modified substrate having a substrate-shaped substrate. [Diagram 2] FIG. 2 is a diagram illustrating the overlap density of the modified base material shown in FIG. (a), (b), and (c) illustrate the cases where the overlap density is 1, 0.7, and 0.5, respectively. [Diagram 3] FIG. 1 is a flow chart showing the process for producing a modified base material according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a flow chart showing the procedure of a method for evaluating a modified substrate according to a third embodiment of the present invention. [Diagram 5] FIG. 1 is a schematic diagram showing the production flow of PEG-modified ND particles (ND-PEG particles). [Figure 6] 1 is a graph showing the relationship between the overlapping density of PEG in ND-PEG particles, the molecular weight of PEG in ND-PEG particles, and the pH of the reaction solution in the production of ND-PEG particles. [Figure 7] 1 is a graph showing the relationship between the overlapping density of PEG in ND-PEG particles, the molecular weight of PEG in ND-PEG particles, and the amount of protein adsorption. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] [Embodiment 1] Hereinafter, a modified base material according to one embodiment of the present invention will be described in detail with reference to FIGS.

[0042] (Overview of modified substrate B) Generally, biomaterials, which are materials that come into direct contact with a living organism or with living cells, suffer from problems such as the adsorption or aggregation of physiological substances present in the living organism onto their surfaces, which inhibits the function of the biomaterial, etc. Modified substrate B according to one embodiment of the present invention is a modified substrate in which the surface of the substrate, which is a biomaterial, has been chemically modified with a hydrophilic polymer in order to prevent physiological substances from being adsorbed or aggregated onto the surface of the substrate.

[0043] (Configuration of modified substrate B) The configuration of the modified base material B will be described with reference to Fig. 1. Fig. 1 is a conceptual diagram for explaining the schematic configuration of the modified base material B.

[0044] As shown in Fig. 1, the modified substrate B includes a substrate 1 and a hydrophilic polymer 2 that chemically modifies the entire surface of the substrate 1. The modified substrate B is associated with an overlapping density. The overlapping density can be used, for example, as an index representing the modification density of the hydrophilic polymer 2 on the surface of the substrate 1 included in the modified substrate B. Details of the method of calculating the overlapping density and the like will be described later with reference to the drawings.

[0045] (Base material 1) The substrate 1 constituting the modified substrate B is a material whose entire surface is chemically modified with a hydrophilic polymer 2. The material constituting the substrate 1 and the shape of the substrate 1 are not particularly limited.

[0046] For example, the material constituting the substrate 1 may be a wide-gap semiconductor containing a color center. A color center is a vacancy generated by replacing an atom in the crystal lattice of a material with another atom, or a vacancy generated by a loss of an atom in the lattice of a material. Examples of such wide-gap semiconductors containing a color center include diamond and silicon carbide. In this embodiment, as an example of a color center, diamond containing an NV center in which a nitrogen atom is adjacent to a vacancy in which a carbon atom is lost, and silicon carbide containing a silicon vacancy, which is a vacancy generated by a loss of a silicon atom, are used as the substrate 1. By adopting such a material as the substrate 1, the modified substrate B can be used as a quantum sensor for acquiring biological information.

[0047] The shape of the substrate 1 may be, for example, a particle shape as shown in Fig. 1(a) or a rectangular parallelepiped base shape as shown in Fig. 1(b), or may be a shape different from a figure that makes it difficult to calculate the surface area based on the shape. A shape different from a figure includes a shape that significantly deviates from a figure shape such as a rectangular parallelepiped or a sphere, and a shape that is approximate to a rectangular parallelepiped or a sphere but has a rough surface, an unintended curved surface, and a curved surface other than a flat surface.

[0048] When the substrate 1 is particulate, its average diameter is preferably 400 μm or less. In addition, when the substrate 1 is particulate and is assumed to be administered into a blood vessel in a living body, the average diameter of the particulate substrate 1 is preferably nanoparticles of 3 nm or more and 500 nm or less, taking into consideration the blood vessel radius of the capillary. In this way, the average diameter of the particulate substrate 1 can be appropriately adjusted depending on the intended use. Here, the average diameter is a diameter obtained by dynamic light scattering, static light scattering, small angle X-ray scattering, fluorescence correlation spectroscopy, transmission electron microscopy, scanning electron microscopy, optical microscopy, or the like. The method for determining the average diameter of the substrate 1 can be appropriately selected from these methods.

[0049] (hydrophilic polymer 2) The hydrophilic polymer 2 constituting the modified substrate B chemically modifies the entire surface of the substrate 1. The hydrophilic polymer 2 is used to prevent physiological substances such as proteins from being adsorbed or aggregated on the surface of the substrate 1. For this reason, in this embodiment, a hydrophilic polymer having biocompatibility (i.e., a biocompatible polymer having hydrophilicity) is adopted as the hydrophilic polymer 2. An example of a criterion for determining whether a hydrophilic polymer is biocompatible is whether it is approved by the Food and Drug Administration (FDA) of the United States of America as being suitable for administration to living organisms. Specific examples of biocompatible hydrophilic polymers include polyacrylic acid (PAA), polymethacrylic acid (PMMA), polyvinyl alcohol (PVA), polysarcosine (PSR), polyaspartic acid (PAsp), polyhydroxyethyl methacrylate (pHEMA), polyethylene glycol (PEG), polyglycerol (PG), and the like. In this embodiment, polyethylene glycol (PEG) or polyglycerol (PG), which are particularly representative of biocompatibility, are adopted as the hydrophilic polymer 2.

[0050] In this embodiment, it is assumed that a substrate that is a biomaterial is used as the modified substrate B, and that the modified substrate B is administered into a living body (more specifically, into a blood vessel). For this reason, in the modified substrate B, a hydrophilic polymer 2 is used as the polymer that modifies the substrate 1. However, in one aspect of the present invention, it is also assumed that the modified substrate B is not administered into a living body, but is used in an organic solvent or oil. In such a case, the polymer that modifies the substrate 1 may be a hydrophobic polymer.

[0051] (overlap density) The overlap density associated with the modified substrate B will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining the overlap density of the modified substrate B.

[0052] The overlapping density is an index representing the modification density of the hydrophilic polymer 2 on the surface of the substrate 1 of the modified substrate B, and represents the degree of overlap between adjacent hydrophilic polymers 2. Such overlapping density is calculated by dividing the average interval L of adjacent hydrophilic polymers 2 by the radius of gyration R, which is the average of the distance from the center of gravity to the end of the hydrophilic polymer 2 when the hydrophilic polymer 2 is regarded as a sphere. g The radius of gyration R is calculated based on the following: g is defined as the square root of the mean square of the distance from the center of gravity to each monomer unit when each hydrophilic polymer 2 modifying the surface of the substrate 1 is regarded as a sphere. Specifically, as shown in FIG. 2, the overlap density is expressed as g Normalized by L / 2R g Here, the average interval L of adjacent hydrophilic polymers 2 depends on the total surface area of ​​the substrate 1 constituting the modified substrate B and the number of hydrophilic polymers 2 chemically modifying the entire surface of the substrate 1.

[0053] L / 2R g The overlap density defined by the formula (1) indicates that the degree of overlap between adjacent hydrophilic polymers 2 is smaller as the overlap density becomes larger, and the degree of overlap between adjacent hydrophilic polymers 2 is larger as the overlap density becomes smaller. For example, as shown in FIG. 2(a), when the overlap density is 1(L / 2R g = 1), it indicates that the spheres representing adjacent hydrophilic polymers 2 are in contact with each other, that is, the adjacent hydrophilic polymers 2 do not overlap. Also, as shown in Figures 2(b) and (c), when the overlap density is smaller than 1 (L / 2R g <1) (e.g., L / 2R g =0.7, L / 2R g=0.5), it indicates a state in which the spheres representing adjacent hydrophilic polymers 2 partially overlap, i.e., adjacent hydrophilic polymers 2 partially overlap, and the overlapping portion increases as the overlap density value decreases. Also, when the overlap density is greater than 1 (not shown), it indicates a state in which the spheres representing adjacent hydrophilic polymers 2 are not in contact and do not overlap, i.e., the surface of the substrate 1 is exposed between the adjacent hydrophilic polymers 2. The modified substrate B in this embodiment employs a configuration in which the entire surface of the substrate 1 is chemically modified with the hydrophilic polymer 2, and therefore the overlap density associated with the modified substrate B is 1 or less.

[0054] As described above, the overlap density is determined by the radius of gyration R , which is derived from the molecular weight of the hydrophilic polymer 2 that chemically modifies the entire surface of the substrate 1. g Therefore, it is a standardized value that is not affected by the molecular weight of hydrophilic polymer 2 or the type of hydrophilic polymer 2. Therefore, the type and molecular weight of hydrophilic polymer 2 in modified substrate B are not limited. In addition, the protein adsorption inhibitory effect of modified substrate B, the entire surface of which has been chemically modified with different types of hydrophilic polymer 2, can be compared in terms of overlapping density values.

[0055] In addition to the overlap density described above, the modified substrate B also has the radius of gyration R g may be further associated.

[0056] [Embodiment 2] A method S1 for producing a modified base material according to another embodiment (embodiment 2) of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0057] The method S1 for producing a modified substrate according to the second embodiment of the present invention is a method for producing a modified substrate B including a substrate 1 and a hydrophilic polymer 2 that chemically modifies the entire surface of the substrate 1. The method S1 for producing the modified substrate B will be described with reference to Fig. 3. Fig. 3 is a flow chart showing the flow of the method S1 for producing the modified substrate B.

[0058] As shown in FIG. 3, the manufacturing method S1 of the modified substrate B includes a chemical modification step S11, a surface area acquisition step S12, an average interval calculation step S13, an overlap density calculation step S14, and an association step S15.

[0059] The chemical modification step S11 is a step of chemically modifying the entire surface of the substrate 1 with a hydrophilic polymer 2. By carrying out this step, a modified substrate B is obtained.

[0060] The surface area acquisition step S12 is a step of obtaining the surface area of ​​the entire surface of the substrate 1 by using a gas adsorption method in the modified substrate B. As an example, in the surface area acquisition step S12, the surface area of ​​the entire surface of the substrate 1 is obtained by using a gas adsorption method in the modified substrate B obtained in the chemical modification step S11, in which the entire surface of the substrate 1 has been chemically modified with the hydrophilic polymer 2.

[0061] In this embodiment, a gas adsorption method is used to more accurately obtain the surface area of ​​the entire surface of the substrate 1 having a shape different from the figure. However, the method for obtaining the surface area of ​​the entire surface of the substrate 1 is not limited to the gas adsorption method, and any method capable of obtaining the surface area of ​​the entire surface of the substrate 1 more accurately can be selected. For example, when the substrate 1 has a figure shape such as a rectangular parallelepiped or a sphere, the surface area may be obtained based on the figure shape. In addition, when the substrate 1 has a spherical shape as an example of a figure shape, the surface area may be obtained based on a dynamic light scattering method.

[0062] The average interval calculation step S13 is a step of calculating the average interval L between adjacent hydrophilic polymers 2 in the modified substrate B. As an example, in the average interval calculation step S13, the average interval L between adjacent hydrophilic polymers 2 is calculated according to the surface area of ​​the entire surface of the substrate 1 acquired in the surface area acquisition step S12 and the number of hydrophilic polymers 2 chemically modifying the entire surface of the substrate 1. Here, the method of determining the number of hydrophilic polymers 2 chemically modifying the entire surface of the substrate 1 is not particularly limited. For example, the number of hydrophilic polymers 2 may be determined by quantifying the hydrophilic polymers 2 by thermogravimetric analysis. Alternatively, the number of hydrophilic polymers 2 may be determined by cutting out the hydrophilic polymers 2 chemically modifying the entire surface of the substrate 1 and quantifying them.

[0063] The overlapping density calculation step S14 is a step of calculating the overlapping density of the modified base material B. As an example, in the overlapping density calculation step S14, the average interval L of the adjacent hydrophilic polymers 2 calculated in the average interval calculation step S13 and the radius of gyration R of the adjacent hydrophilic polymers 2 are calculated. g The overlap density is calculated based on the average interval L of the adjacent hydrophilic polymers 2 and the radius of gyration R of the adjacent hydrophilic polymers 2. g Normalized by L / 2R g is defined as:

[0064] The associating step S15 is a step of associating the overlap density with the modified base material B. As an example, in the associating step S15, the overlap density calculated in the overlap density calculation step S14 is associated with the modified base material B obtained in the chemical modification step S11.

[0065] By carrying out each step included in the manufacturing method S1 for a modified substrate according to this embodiment, a modified substrate B can be obtained in which the entire surface of a substrate 1 is chemically modified with a hydrophilic polymer 2, and the overlapping density of the hydrophilic polymer 2 included in the modified substrate B is associated with the modified substrate B. Furthermore, by carrying out each step included in the manufacturing method S1, the overlapping density can be accurately calculated even for a modified substrate B composed of a substrate 1 (e.g., nanodiamond particles) having a shape different from a figure shape. Therefore, a modified substrate B associated with an accurate overlapping density can be obtained.

[0066] [Embodiment 3] The evaluation method S2 for a modified substrate according to another embodiment (embodiment 3) of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0067] The evaluation method S2 of a modified substrate according to the third embodiment of the present invention is a method for evaluating the overlapping density of a modified substrate B comprising a substrate 1 and a hydrophilic polymer 2 chemically modifying the entire surface of the substrate 1. The evaluation method S2 of the modified substrate B will be described with reference to Fig. 4. Fig. 4 is a flow chart showing the flow of the manufacturing method S1 of the modified substrate B.

[0068] The evaluation method S2 of the modified substrate B includes a surface area acquisition step S12, an average interval calculation step S13, an overlap density calculation step S14, and an evaluation step S25, as shown in Fig. 4. The surface area acquisition step S12, the average interval calculation step S13, and the overlap density calculation step S14 included in the evaluation method S2 of the modified substrate B are similar to the steps described above, and therefore will not be described repeatedly here.

[0069] The evaluation step S25 is a step of evaluating the modified substrate B. As an example, in the evaluation step S25, the overlap density of the hydrophilic polymer 2 in the modified substrate B calculated in the overlap density calculation step S14 is evaluated. For example, the smaller the value of the overlap density of the hydrophilic polymer 2 in the modified substrate B, the larger the overlap of adjacent hydrophilic polymers 2, and the hydrophilic polymer 2 is evaluated to have modified the surface of the substrate 1 at a high density. In addition, the larger the value of the overlap density of the hydrophilic polymer 2 in the modified substrate B, the smaller the overlap of adjacent hydrophilic polymers 2, and the hydrophilic polymer 2 is evaluated to have modified the surface of the substrate 1 at a low density.

[0070] By carrying out each step included in the evaluation method S2 of the modified substrate according to this embodiment and evaluating the overlapping density of the hydrophilic polymer 2 in the modified substrate B, the chemical modification by the hydrophilic polymer 2 on the entire surface of the substrate 1 constituting the modified substrate B can be quantitatively indicated. In addition, by carrying out each step included in the evaluation method S2 and evaluating the overlapping density of the hydrophilic polymer 2 in the modified substrate B, the protein adsorption inhibitory effect of the modified substrate B can be evaluated. Note that the overlapping density calculated in this evaluation method S2 is a value that does not depend on the type or molecular weight of the hydrophilic polymer 2 constituting the modified substrate B, and is also a value that does not depend on the shape of the substrate 1 constituting the modified substrate B. Therefore, evaluation of the protein adsorption inhibitory effect using the overlapping density can be a general evaluation method.

[0071] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0072] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples. In this example, the present invention will be described in more detail using the example where modified substrate B is PEG-modified nanodiamond (ND-PEG) particles, that is, substrate 1 is nanodiamond (ND) particles, and hydrophilic polymer 2 is PEG.

[0073] (Production of ND-PEG particles) The production of ND-PEG particles according to this example will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing the flow of production of PEG-modified ND particles (ND-PEG particles).

[0074] As shown in Figure 5, ND-PEG particles were obtained by adding N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to a solvent in which carboxylic acid-introduced nanodiamond particles (ND-COOH) were dispersed, and then adding α-methoxy-ω-amino-PEG (PEG-NH2) and reacting the mixture.

[0075] Specifically, ND particles with a nominal particle size of 50 nm were first heated and oxidized at 515°C for two hours in air. The heated and oxidized ND particles were dispersed in a mixed solution of sulfuric acid and nitric acid (3:1 v / v), redispersed using an ultrasonic disintegrator, and reacted at 300°C for one hour while stirring. After purification, ND-COOH was obtained by freeze-drying.

[0076] Next, ND-COOH was dispersed in water, and NHS, EDC, and PEG-NH2 were added. Here, NHS and EDC were 20 and 2 equivalents of carboxylic acid, respectively. In addition, PEG-NH2 was added at the overlap concentration (C * The concentration was double that of the overlapping concentration (C *) is the concentration at which the polymer chains of a polymer begin to come into contact with each other as the concentration of the dissolved polymer increases in a polymer solution. After ultrasonic treatment, these reaction solutions were stirred overnight at 50°C on a hot stirrer to add PEG. The reaction solutions were then purified and freeze-dried to obtain ND-PEG particles. The addition of PEG to the ND particles was confirmed using a Fourier transform infrared spectrophotometer.

[0077] (Evaluation of manufacturing conditions) Using ND-PEG particles modified with PEG of different molecular weights and ND-PEG particles produced using reaction solutions with different pHs, the relationship between the overlapping density of PEG in ND-PEG particles, the molecular weight of PEG in ND-PEG particles, and the pH of the reaction solution in the production of ND-PEG particles was evaluated. The ND-PEG particles modified with PEG of different molecular weights were obtained by adding PEG-NH2 of different molecular weights in the production of ND-PEG particles. The pH of the reaction solution was adjusted by adding HCl.

[0078] In this evaluation, the amount of PEG added to the ND-PEG particles was determined by thermally decomposing the PEG in a nitrogen atmosphere using a thermogravimetric analyzer for ND-PEG particles modified with PEG of different molecular weights and ND-PEG particles produced using reaction solutions with different pH values. The surface area of ​​the ND particles was also determined using a gas adsorption method. The average distance L between adjacent PEGs was calculated based on the amount of PEG added and the surface area of ​​the ND particles, and the radius of gyration R of the PEG was calculated. g The overlap density normalized by L / 2R gwas calculated. FIG. 6 shows the relationship between the overlap density of PEG in the ND-PEG particles, the molecular weight of PEG in the ND-PEG particles, and the pH of the reaction solution in the production of ND-PEG particles. As shown in FIG. 6, the overlap density value of the ND-PEG particles increases as the molecular weight of PEG increases, and the pH of the reaction solution increases in the order of pH 10-11 (basic), pH 4 (acidic), and pH 7 (neutral). In other words, it was revealed that the ND-PEG particles achieve high-density modification with PEG as the molecular weight of PEG increases, and the pH of the reaction solution increases in the order of pH 10-11 (basic), pH 4 (acidic), and pH 7 (neutral).

[0079] (Evaluation of protein adsorption inhibition effect) Using ND-PEG particles modified with PEG of different molecular weights, the relationship between the overlapping density of PEG in the ND-PEG particles, the molecular weight of PEG in the ND-PEG particles, and the amount of protein adsorption was evaluated.

[0080] In this evaluation, albumin, which is the most abundant protein in blood, was used as a representative protein. Bovine serum albumin (BSA) was dissolved at 2 mg / ml in a physiological salt concentration buffer (10 mM HEPES, 150 mM NaCl, pH = 7.4). Untreated ND particles (ND-pristine) and ND-PEG particles modified with PEG with molecular weights of 2k, 5k, 12k, 20k, and 40k were added to a physiological salt concentration buffer and redispersed (20 mg / ml) using an ultrasonic disrupter. Equal amounts of the BSA solution and the ND particle dispersion were mixed (final concentrations were ND particle dispersion: 10 mg / ml, BSA solution: 1 mg / ml) and kept at 37°C for 5 hours. The ND particles in the mixture were precipitated by centrifugation, and the amount of remaining BSA in the supernatant was determined by colorimetry using a BCA protein assay (Thermo Fisher Scientific, Waltham, MA) and an ultraviolet-visible spectrophotometer, and the amount of BSA adsorbed to the ND particles was calculated. Figure 7 shows the relationship between the overlap density of PEG in the ND-PEG particles, the molecular weight of PEG in the ND-PEG particles, and the amount of protein adsorption. As shown in Figure 7, the ND-PEG particles showed that the larger the PEG molecular weight, the smaller the overlap density of PEG, indicating that PEG was highly densely modified. In addition, a correlation was revealed in which the smaller the overlap density, i.e., the more densely PEG was modified in the ND-PEG particles, the better the albumin adsorption inhibitory effect. [Industrial Applicability]

[0081] The present invention can be used as a quantum sensor for acquiring biological information. [Explanation of symbols]

[0082] B Modified substrate 1 Base material 2. Hydrophilic polymers

Claims

1. A modified substrate comprising a substrate and a polymer chemically modifying an entire surface of the substrate, (1) an average distance between adjacent polymers on the entire surface, the average distance corresponding to the surface area of ​​the entire surface and the number of the polymers chemically modified on the entire surface; and (2) an overlap density calculated based on the radius of gyration of the polymers chemically modifying the entire surface, are associated with the modified substrate. A modified substrate comprising:

2. The modified substrate is further associated with the radius of gyration. The modified substrate according to claim 1 .

3. The substrate is composed of a wide-gap semiconductor containing a color center. The modified substrate according to claim 1 or 2.

4. The substrate is a particle having an average diameter of 400 μm or less. The modified substrate according to claim 1 or 2.

5. The substrate is a particle having an average diameter of 3 nm or more and 500 nm or less. The modified substrate according to claim 4 .

6. The polymer is a hydrophilic polymer. The modified substrate according to claim 1 or 2.

7. The polymer is a biocompatible polymer. The modified substrate according to claim 1 or 2.

8. The polymer is polyethylene glycol or polyglycerol. The modified substrate according to claim 1 or 2.

9. The overlap density is 1 or less. The modified substrate according to claim 1 or 2.

10. The shape of the modified substrate is different from the figure; The modified substrate according to claim 1 or 2.

11. 1. A method for producing a modified substrate comprising a substrate and a polymer chemically modifying an entire surface of the substrate, the method comprising: a surface area acquisition step of acquiring a total surface area of ​​the entire surface of the modified substrate, the entire surface of which has been chemically modified with the polymer, by a gas adsorption method; an average distance calculation step of calculating an average distance between adjacent polymers on the entire surface, the average distance being based on the total surface area and the number of the polymers chemically modified on the entire surface; The overlap density calculation step includes calculating an overlap density based on the average interval and the radius of gyration of the polymer chemically modifying the entire surface. A method for producing a modified substrate, comprising:

12. The method further includes a step of associating the overlap density with the modified substrate, the step being performed after the overlap density calculation step. The method for producing a modified substrate according to claim 11 .

13. The method further includes a chemical modification step performed before the surface area acquisition step, in which the entire surface is chemically modified with a polymer. The method for producing a modified substrate according to claim 11 or 12.

14. 1. A method for evaluating overlap density in a modified substrate comprising a substrate and a polymer chemically modifying an entire surface of the substrate, the method comprising: a surface area acquisition step of acquiring a total surface area of ​​the entire surface of the modified substrate, the entire surface of which has been chemically modified with the polymer, by a gas adsorption method; an average distance calculation step of calculating an average distance between adjacent polymers on the entire surface, the average distance being based on the total surface area and the number of the polymers chemically modified on the entire surface; The overlap density calculation step includes calculating an overlap density based on the average interval and the radius of gyration of the polymer chemically modifying the entire surface. A method for evaluating overlap density in a modified substrate, comprising:

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