Surface-modified metal-containing silica particles, contrast agent, method for producing metal-containing silica particles, and method for producing surface-modified metal-containing silica particles

Abstract

To provide a material exhibiting high blood retention capability, allowing temporal observation, having excretability from the body, and offering high biocompatibility.SOLUTION: A surface-modified metal-containing silica particle is characterized by containing, inside the particle, a plurality of biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group, and is characterized in that polyethylene glycol chains are present on the particle surface.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to surface-modified metal-containing silica particles, a contrast agent using the same, a method for producing metal-containing silica particles, and a method for producing surface-modified metal-containing silica particles. [Background technology]

[0002] In the medical field, diagnostic imaging is an effective method for diagnosing diseases and identifying the source of pathogens. Diagnostic imaging utilizes differences in X-ray absorption rates and magnetic properties of internal substances to image blood vessels and organs, allowing for visual diagnosis of the inside of the body from the outside. Examples of diagnostic imaging include X-ray computed tomography (CT), magnetic resonance imaging (MRI), position emission tomography (PET)-CT, fluorescence imaging, and ultrasound.

[0003] When using diagnostic imaging methods to fluoroscopically or photograph diseased tissues in the body, it is extremely difficult to determine the slight difference in contrast between normal tissue and the diseased tissue from the image. Therefore, high-precision diagnosis requires high contrast and observation of changes over time. Currently, a method is used that uses contrast agents to increase the contrast ratio between diseased tissue and normal tissue.

[0004] In X-ray CT scans, barium or iodine-based contrast agents are generally used as contrast agents, but the iodine-based contrast agents used in X-ray CT scans are known to cause serious side effects such as shortness of breath, loss of consciousness, and low blood pressure in a certain percentage of cases.

[0005] Here, gold (Au) and platinum (Pt) have high atomic numbers and therefore have higher X-ray absorption capabilities than commercially available X-ray contrast agents such as barium and iodine. Furthermore, contrast agents using gold (Au) and platinum (Pt) have a significantly different structure from existing iodine-based contrast agents, and are expected to have fewer side effects than existing iodine-based contrast agents. Therefore, nanoparticles of Au or Pt used as contrast agents are expected to be used in safe X-ray CT examinations, providing high contrast and eliminating the risk of iodine-related side effects that are a problem with iodine-based contrast agents.

[0006] Patent Document 1 discloses a composition containing colloidal metals, including colloidal Au nanoparticles, and a method for the delivery of drugs to desired cells or sites. The composition includes a platform (such as a colloidal metal sol) for constructing nanodrugs, a targeting ligand, a stealth agent (such as polyethylene glycol for neutralizing the nanoparticle drug and thereby preventing its uptake by the reticuloendothelial system), and one or more active agents or drugs.

[0007] Patent Document 2 discloses encapsulated dye-coated precious metal nanoparticles as contrast agents. The nanoparticles have a preferred size of 2 to 1000 nm and comprise a linker material (such as glutathione) of 0.1 to 10 nm in length bound to the surface of the precious metal nanoparticles, a layer of dye molecules bound to the linker material, and an inorganic oxide coating layer such as silica of 0.1 to 100 nm in thickness.

[0008] Non-Patent Document 1 discloses a biodegradable nanostructure with a particle diameter of 100 nm for photoacoustic imaging. This biodegradable nanostructure was synthesized by coating Au nanoparticles with poly(sodium 4-styrenesulfonate), adsorbing them onto dye-modified poly(L-lysine) through ionic interactions, and using the resulting nanoparticle as a template for silica coating. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2011-520769 [Patent Document 2] Patent No. 6602202 [Non-patent literature]

[0010] [Non-Patent Document 1] Ajlan Al Zaki, Daniel Joh, Zhiliang Cheng, Andre Lu1s Branco De Barros, Gary Kao, Jay Dorsey, Andrew Tsourkas, J. Am. Chem. Soc., 8 (2014) 104-112. Summary of the Invention [Problem to be solved by the invention]

[0011] Iodine contrast agents used as X-ray contrast agents are small molecules with a short blood retention time and are excreted within a few minutes. Increasing blood retention time improves the efficiency of blood vessel visualization and evaluation of tumor vascular extravasation. On the other hand, if blood retention time is too long, excretion ability decreases, raising concerns about adverse effects on the body. Therefore, the optimal contrast agent is one that remains in the blood for a certain period of time and is then quickly excreted.

[0012] From this perspective, when metal nanoparticles such as Au nanoparticles or Pt nanoparticles are used as contrast agents, if the particle size is smaller than the pores in the glomerular basement membrane of the kidney, they can pass through the pores and be excreted from the body, but metal nanoparticles with a particle size smaller than the pores have a short retention time in the blood and can be rapidly excreted from the kidney, which raises concerns that this may make it difficult to observe microvessels over time.On the other hand, when metal nanoparticles with a particle size larger than the pores in the glomerular basement membrane are used as contrast agents, they have a long retention time in the blood, but there is a concern that the metal nanoparticles may remain in the body after imaging, making their excretion from the body difficult.

[0013] In the composition of Patent Document 1, the preferred size of the core colloidal Au nanoparticles is 1 to 40 nm, but larger sizes result in poor excretion from the body, while smaller sizes result in poor retention in the blood.

[0014] For the precious metal nanoparticles of Patent Document 2, it is possible to ensure retention in blood by adjusting the length of the linker material and the thickness of the inorganic oxide coating layer, and to ensure excretion from the body after decomposition by reducing the size of the precious metal nanoparticles. However, Patent Document 2 does not specify the number of precious metal nanoparticles in a particle, and there may be, for example, one core precious metal nanoparticle. Particles with a thick linker material or coating layer compared to the core size have a low CT value per unit concentration, and X-ray contrast performance is low in blood, where the concentration of contrast agent particles is maintained low.

[0015] In the biodegradable nanostructures described in Non-Patent Document 1, the template polylysine has cell adsorption properties, and poly(sodium styrene sulfonate) has potassium exchange properties, so there is a risk of unexpected interactions with biological components. Furthermore, in the in vivo environment where silica decomposes but polylysine does not, Au nanoparticles will not be released.

[0016] As described above, conventional methods had problems such as: 1) low blood retention making it impossible to observe over time, 2) difficulty in excreting from the body, and 3) low biocompatibility.

[0017] Furthermore, the above 1) to 3) also pose problems in drug delivery systems for drugs such as anticancer drugs, antibody drugs, proteins, peptides, anti-TNFs, immunomodulators, cytokines, chemo-cytokines, anti-neoplasms, analgesics, anti-inflammatory drugs, anti-adrenergic drugs, local anesthetics, genome editing enzymes, photothermal therapy agents using gold nanoparticles or platinum nanoparticles, imaging agents, biomarkers, biosensors, etc.

[0018] Therefore, an object of the present invention is to provide a material that has high retention in blood, allows for observation over time, is excretable from the body, and is highly biocompatible. [Means for solving the problem]

[0019] In light of the above-mentioned circumstances, the present inventors have conducted extensive research and have found that by modifying the surfaces of metal nanoparticles (Au nanoparticles or Pt nanoparticles) of a size that can be excreted from the body with biocompatible molecules, incorporating a plurality of such biocompatible molecule-modified metal nanoparticles into silica particles, and having polyethylene glycol chains present on the surfaces of the silica particles, when used for imaging or the like, the metal nanoparticles exist in a state where they are contained in silica particles with large particle sizes, thereby increasing the blood residence time and enabling the observation of microvessels over time, and after use, the silica particles decompose and exist in the body in the form of small metal nanoparticles that can be excreted from the body, and because the silica particles have polyethylene glycol chains present on their surfaces, they become a highly biocompatible material, which led to the completion of the present invention.

[0020] That is, the present invention (1) provides surface-modified metal-containing silica particles characterized in that the particles contain multiple biocompatible molecule-modified metal nanoparticles inside, in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, and polyethylene glycol chains are present on the particle surface.

[0021] The present invention (2) also provides surface-modified metal-containing silica particles (1), characterized in that the particle surface is chemically modified with a surface modifier having a polyethylene glycol chain.

[0022] The present invention (3) also provides surface-modified metal-containing silica particles (1), characterized in that the silica particles have PEG-modified metal nanoparticles, which are Au nanoparticles or Pt nanoparticles surface-modified with a surface modifier having a polyethylene glycol chain, electrostatically adsorbed to the particle surface.

[0023] The present invention (4) also provides surface-modified metal-containing silica particles according to any one of (1) to (3), characterized in that the biocompatible molecule is a compound selected from the group consisting of glutathione, cysteine, cysteamine, polyethylene glycol having an amino group at one end of the polyethylene glycol chain and a thiol group at the other end, and polyethylene glycol having a carboxyl group at one end of the polyethylene glycol chain and a thiol group at the other end.

[0024] The present invention (5) also provides the surface-modified metal-containing silica particles according to any one of (1) to (4), wherein the particle diameter of the biocompatible molecule-modified metal nanoparticles is 15 nm or less.

[0025] The present invention (6) also provides the surface-modified metal-containing silica particles according to any one of (1) to (5), characterized in that the particle diameter is greater than 15 nm and equal to or less than 1 μm.

[0026] The present invention (7) also provides a contrast agent comprising the surface-modified metal-containing silica particles of any one of (1) to (6).

[0027] The present invention (8) also provides a reaction raw material liquid preparation step of adding tetraalkoxysilane or a derivative thereof to a colloidal solution containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material liquid; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; The present invention provides a method for producing metal-containing silica particles, which is characterized by having the following:

[0028] The present invention (9) also provides a reaction raw material liquid preparation step of adding tetraalkoxysilane or a derivative thereof to a colloidal solution containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material liquid; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; a biocompatible molecular chain introduction step of introducing biocompatible molecular chains into the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; The present invention provides a method for producing surface-modified metal-containing silica particles, which is characterized by having the following:

[0029] The present invention (10) also provides a method for producing surface-modified metal-containing silica particles (9), characterized in that the biocompatible molecular chain introduction step is a polyethylene glycol chain introduction step of introducing a polyethylene glycol chain into the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles.

[0030] Further, the present invention (11) is directed to a method for introducing a polyethylene glycol chain, comprising the steps of: an amino group-modified silica particle producing step of adding an amino group modifying agent to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the amino group-modified metal-containing silica particles; a surface-modified metal-containing silica particle producing step of adding a surface modifier having a polyethylene glycol chain to the colloidal solution of the amino group-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; The present invention also provides a method for producing surface-modified metal-containing silica particles according to (10), which is characterized by carrying out the steps of:

[0031] Further, the present invention (12) provides a method for introducing a polyethylene glycol chain, comprising the steps of: a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the cationic polymer-modified metal-containing silica particles; a surface-modified metal-containing silica particle production step in which Au nanoparticles or Pt nanoparticles are added as metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles, and then a surface modifier having a polyethylene glycol chain is added to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; The present invention also provides a method for producing surface-modified metal-containing silica particles according to (10), which is characterized by carrying out the steps of:

[0032] Further, the present invention (13) provides a method for introducing a polyethylene glycol chain, comprising the steps of: a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the cationic polymer-modified metal-containing silica particles; a PEG-modified metal nanoparticle generation step of adding a surface modifier having a polyethylene glycol chain to a solution containing Au nanoparticles or Pt nanoparticles as metal nanoparticles to generate PEG-modified metal nanoparticles; a surface-modified metal-containing silica particle producing step of adding the PEG-modified metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; The present invention also provides a method for producing surface-modified metal-containing silica particles according to (10), which is characterized by carrying out the steps of: [Effects of the Invention]

[0033] According to the present invention, it is possible to provide a material that has high retention in blood, allows for observation over time, is excretable from the body, and is highly biocompatible. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 shows a TEM image of the AuGSH nanoparticles of Example 1. [Figure 2] FIG. 1 shows the FT-IR spectrum of the AuGSH nanoparticles of Example 1. [Figure 3] FIG. 1 shows a TEM image of the AuGSH / SiO2 nanoparticles of Example 1. [Figure 4] FIG. 1 shows the FT-IR spectrum of the AuGSH / SiO2 nanoparticles of Example 1. [Figure 5] FIG. 1 shows a TEM image of the AuGSH / SiO 2 NH 2 nanoparticles of Example 1. [Figure 6] FIG. 1 shows a TEM image of the AuGSH / SiO 2 NH 2 / PEG nanoparticles of Example 1. [Figure 7] FIG. 1 shows a TEM image of the AuGSH / SiO 2 PDADMAC / AuPEG nanoparticles of Example 2. [Figure 8] FIG. 10 shows DLS in Example 2. [Figure 9] FIG. 1 shows UV-vis in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0035] The surface-modified metal-containing silica particles of the present invention are surface-modified metal (Au or Pt)-containing silica particles characterized in that they contain multiple biocompatible molecule-modified metal nanoparticles inside the particles, in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, and polyethylene glycol chains are present on the particle surface.

[0036] The surface-modified metal-containing silica particles of the present invention contain Au nanoparticles or Pt nanoparticles. Due to their high electron density, Au and Pt have the property of strongly absorbing X-rays and electron beams, resulting in high X-ray absorption. Therefore, Au and Pt are expected to be used as X-ray CT contrast agents. Furthermore, Au and Pt are expected to be used in drug delivery systems for drugs such as anticancer drugs, antibody drugs, proteins, peptides, anti-TNFs, immunomodulators, cytokines, chemo-cytokines, anti-neoplasms, analgesics, anti-inflammatory drugs, anti-adrenergic drugs, local anesthetics, and genome-editing enzymes, as well as photothermal therapy agents, imaging agents, biomarkers, biosensors, and the like, using Au or Pt nanoparticles.

[0037] The surface-modified metal-containing silica particles of the present invention contain Au nanoparticles or Pt nanoparticles as metal nanoparticles. In the surface-modified metal-containing silica particles of the present invention, the Au nanoparticles or Pt nanoparticles are primarily zero-valent metal particles. Furthermore, the Au nanoparticles or Pt nanoparticles may have a portion of their surface ionized and / or complex-ionized. The Au nanoparticles or Pt nanoparticles in the surface-modified metal-containing silica particles of the present invention are produced by physical pulverization of bulk metal or by a method of generating metal atoms and agglomerating them (agglomeration method). The agglomeration method can easily produce high-purity Au nanoparticles or Pt nanoparticles. Agglomeration methods are divided into dry and wet methods. Dry methods include CVD, which generates gold or platinum atoms by decomposition of a precursor. Meanwhile, wet methods, which generate zero-valent metal atoms from a precursor in a liquid, utilize reduction from a metal salt or thermal decomposition of a metal complex. Wet methods often involve reduction using alcohol, hydrazine, or organic acid.

[0038] In the surface-modified metal-containing silica particles of the present invention, the Au or Pt nanoparticles are present in the form of metal nanoparticles surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group (hereinafter also referred to as biocompatible molecule-modified metal nanoparticles). When Au or Pt nanoparticles are used in vivo as contrast agents, drug delivery systems, etc., there is a problem that they remain in the body after use. Therefore, it is desirable that Au or Pt nanoparticles (hereinafter collectively referred to as metal nanoparticles) are administered into the body and excreted from the body after their intended use. When metal nanoparticles are excreted from the body, for example, through the glomerular basement membrane of the kidney, metal nanoparticles larger than the pore size of the glomerular basement membrane of the kidney cannot be excreted. Therefore, the particle size of the metal nanoparticles must be smaller than the pore size of the glomerular basement membrane of the kidney. However, metal nanoparticles tend to aggregate more easily as their particle size decreases, so simply reducing the particle size of each particle results in the particles aggregating into large aggregates that cannot pass through the glomerular basement membrane of the kidney. Therefore, in the surface-modified metal-containing silica particles of the present invention, the surface of the metal nanoparticles is modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, thereby preventing aggregation of small metal nanoparticles. Furthermore, because the metal nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, their biocompatibility is increased, making them less likely to cause a foreign body reaction.

[0039] The biocompatible molecule having a thiol group and an amino group and / or a carboxyl group in the surface-modified metal-containing silica particles of the present invention has a thiol group, an amino group, and a carboxyl group in the molecule, or a thiol group and an amino group, or a thiol group and a carboxyl group, and is biocompatible. Biocompatible molecules having a thiol group and an amino group and / or a carboxyl group prevent aggregation of metal nanoparticles in the body and also contribute to reducing the particle size of metal nanoparticles and improving their dispersibility during production. In the present invention, "biocompatible" refers to having affinity with living tissue and being less likely to cause rejection.

[0040] Examples of biocompatible molecules having a thiol group and an amino group and / or a carboxyl group for the surface-modified metal-containing silica particles of the present invention include compounds selected from the group consisting of glutathione (GSH), cysteine, cysteamine, polyethylene glycol having an amino group at one end of the polyethylene glycol chain and a thiol group at the other end (NH2-PEG(polyethylene glycol)-SH), and polyethylene glycol having a carboxyl group at one end of the polyethylene glycol chain and a thiol group at the other end (COOH-PEG(polyethylene glycol)-SH). When the biocompatible molecule having a thiol group and an amino group and / or a carboxyl group is one of the above compounds, aggregation of metal nanoparticles in the body is prevented, and the effects of reducing the particle size of the metal nanoparticles and improving dispersibility during production are enhanced.

[0041] When the surface-modified metal-containing silica particles of the present invention are used as a material for a contrast agent, controlling the dispersion and aggregation of the metal nanoparticles is important for efficiently exhibiting their properties. In the surface-modified metal-containing silica particles of the present invention, the surfaces of the metal nanoparticles are chemically modified with the biocompatible molecules described above in order to improve the dispersibility of the metal nanoparticles in various solvents. This not only prevents the aggregation of the metal nanoparticles and improves their affinity for the solvent, but also generates steric hindrance and electrostatic interactions between the particles, thereby improving the dispersibility.

[0042] The method for producing biocompatible molecule-modified metal nanoparticles is not particularly limited, but examples include a method in which a metal salt (Au salt or Pt salt) is reduced with a reducing agent in the presence of a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group, thereby reducing metal ions (Au ions or Pt ions) to produce Au nanoparticles or Pt nanoparticles, and then a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group is reacted with the metal on the surface of the produced Au nanoparticles or Pt nanoparticles. Metal salts include HAuCl4 and its hydrate, NaAuCl4 and its hydrate, KAuCl4 and its hydrate, gold hydroxide (III) Au(OH)3, digold trioxide Au2O3, digold trisulfide Au2S3, gold chloride (III) AuCl3, gold chloride (I) AuCl, ammonium tetrachloroaurate or its hydrate, lithium tetrachloroaurate or its hydrate, gold iodide, gold bromide, gold acetate, platinum oxide, platinum chloride, platinum bromide, platinum iodide, hexachloroplatinic (IV) acid and its hydrate, hexachloroplatinic acid (IV) and its hydrate, and hexachloroplatinic acid (IV). Examples include sodium gold(IV) and its hydrate, potassium hexachloroplatinate(IV), sodium tetrachloroplatinate(II) and its hydrate, potassium tetrachloroplatinate(II), ammonium hexabromoplatinate(IV), potassium tetrabromoplatinate(II), potassium hexaiodoplatinate(IV), ammonium tetrachloroplatinate(II), dihydrogen hexahydroxyplatinate(IV), sodium hexahydroxyplatinate(IV), and tetraamineplatinum(II) hydroxide. Examples of reducing agents for reducing metal salts include tetrakis(hydroxymethyl)phosphonium chloride, sodium borohydride, citric acid and its salts, citric acid hydrate, hydrazine and its salts, borohydride salts, sulfate, thiosulfate, tartrate, phosphinic acid and its salts, formic acid and its salts, acetic acid and its salts, propionic acid and its salts, oxalic acid and its salts, ascorbic acid and its salts, phosphoric acid and its salts, hypophosphorous acid and its salts (e.g., sodium hypophosphite (NaH2PO2)), transition metal salts, glycine, dimethylamine borane, fructose, glycerol, acetaldehyde, glucose, cellulose, carboxymethyl cellulose, formaldehyde, ascorbic acid, and sugar decomposition products.

[0043] The biocompatible molecule-modified metal nanoparticles are formed by reacting Au or Pt on the particle surface of Au or Pt nanoparticles with the thiol group of a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group. That is, the biocompatible molecule-modified metal nanoparticles consist of Au or Pt nanoparticles and the reaction residue of the biocompatible molecule having a thiol group and an amino group and / or a carboxyl group that is bound to the surface of the Au or Pt nanoparticles.

[0044] The surface-modified metal-containing silica particles of the present invention are silica particles containing multiple, preferably 3 or more, and more preferably 5 or more, "biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group" within a single silica particle. Therefore, the surface-modified metal-containing silica particles of the present invention contain two or more, preferably 3 or more, and more preferably 5 or more metal nanoparticles within the particle. By containing multiple metal nanoparticles, metal nanoparticles with small particle sizes are concentrated on multiple silica particles, resulting in an increased CT value per unit concentration, enabling both high X-ray contrast and excretion from the body after degradation. Metal nanoparticles appear as black dots during transmission electron microscope (TEM) observation due to their low electron transmittance. Therefore, the number of metal nanoparticles in a TEM image can be measured by visual inspection of the TEM image or by image analysis. In the following, silica particles containing multiple, preferably 3 or more, and more preferably 5 or more, "biocompatible molecule-modified metal nanoparticles whose surface is modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group" will also be referred to as metal-containing silica particles.

[0045] In the surface-modified metal-containing silica particles of the present invention, a plurality of biocompatible molecule-modified metal nanoparticles are present within the silica particle in a state where they are not aggregated but are closely gathered together.

[0046] The particle diameter of the surface-modified metal nanoparticles in the surface-modified metal-containing silica particles of the present invention is preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, and more preferably 1 to 5 nm. For example, when metal nanoparticles are used in vivo as contrast agents or drug delivery systems, the metal nanoparticles must be excreted from the body after use. When the particle diameter of the surface-modified metal nanoparticles in the surface-modified metal-containing silica particles of the present invention is within the above range, they can easily pass through the glomerular basement membrane of the kidney, enabling them to be excreted from the body.

[0047] The surface-modified metal-containing silica particles of the present invention are silica particles having polyethylene glycol chains present on the particle surface. Biocompatible molecule-modified metal nanoparticles surface-modified with biocompatible molecules having thiol groups and amino and / or carboxyl groups, particularly those with particle diameters of preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, and more preferably 1 to 5 nm, can pass through the glomerular basement membrane of the kidney and are therefore excreted from the body. However, if left untreated, their short blood residence time makes it difficult to observe microvascular structures over time. Therefore, the surface-modified metal-containing silica particles of the present invention are made of silica (SiO2), a low-toxicity and biodegradable material, and contain biocompatible molecule-modified metal nanoparticles surface-modified with biocompatible molecules having thiol groups and amino and / or carboxyl groups. Furthermore, the surface-modified metal-containing silica particles of the present invention contain multiple metal nanoparticles within the silica particles. Due to their large particle size, they are less likely to be excreted immediately after administration, allowing for increased blood retention during use. Furthermore, after use, the silica is decomposed in the blood, and after the silica decomposition, biocompatible molecule-modified metal nanoparticles, surface-modified with biocompatible molecules having thiol groups and amino and / or carboxyl groups, remain in the body. Furthermore, because each biocompatible molecule-modified metal nanoparticle has a small particle size, it can be excreted by the kidneys. Furthermore, because silica particles have a negative charge on their surface, they are easily modified by electrostatic interactions. Furthermore, because silica particles have numerous silanol groups on their surface for forming siloxane bonds, they can easily be surface-modified with silane coupling agents, surface modifiers having polyethylene glycol chains, polypeptides, water-soluble polymers (e.g., polyvinylpyrrolidone, chitin, chitosan, polyethylene glycol, polyvinyl alcohol, dextran, alginic acid), and the like. Furthermore, silica is inert to the living body and decomposes in human plasma, and therefore is highly biocompatible.

[0048] In the surface-modified metal-containing silica particles of the present invention, the silica particles are produced by polymerization of tetraalkoxysilane in a mixed solution using, for example, tetraalkoxysilane as a monomer, HO as a reaction initiator, and a lower alcohol as a solvent. The elementary reactions of this polymerization are the hydrolysis reaction of formula (1) and the polycondensation reactions of formulas (2) and (3). The tetraalkoxysilane monomer undergoes hydrolysis in the alcohol solvent, and the products undergo dehydration and dealcoholization polycondensation with each other or with the monomer to produce silica. Formula (4) represents the overall reaction. Hydrolysis reaction (RO)3Si-OR+H2O→(RO)3Si-OH+ROH (1) Polycondensation reaction Dehydration: (RO)3Si-OH+HO-Si(OR)3→(RO)3Si-O-Si(OR)3+H2O (2) Dealcoholization: (RO)3Si-OR + HO-Si(OR)3 → (RO)3Si-O-Si(OR)3 + ROH (3) Overall reaction Si(OR)4 + 2H2O → SiO2 + 4ROH (4) R represents an alkyl group, C x H 2x+1 The hydrolysis reaction is a reaction that replaces an alkoxyl group with a hydroxyl group. There are two condensation reactions: one that produces water and one that produces alcohol.

[0049] Since the hydrolysis of silicon alkoxide polymerization is relatively slow, an acid or base is often added as a catalyst to accelerate the reaction. + is hydrolyzed by an electrophilic substitution reaction in which the O in the OR group attacks the O. On the other hand, in the case of a basic catalyst, OH -It is believed that hydrolysis proceeds through a nucleophilic reaction in which OR bonds with Si in Si(OR)4 and OR is released from Si as OR-. There are no particular limitations on the method for producing silica particles containing metal nanoparticles, but for example, silica particles can be obtained by adding tetraethoxysilane (TEOS) as an SiO2 source to a colloidal solution of biocompatible molecule-modified metal nanoparticles whose surfaces have been modified with biocompatible molecules having thiol groups and amino and / or carboxyl groups, and then adding NH4OH as a basic catalyst to produce silica particles.

[0050] The surface-modified metal-containing silica particles of the present invention are silica particles having polyethylene glycol chains present on their surface. The surface-modified metal-containing silica particles of the present invention focus on polyethylene glycol (PEG), a biocompatible material, and have polyethylene glycol chains present on the surface of the metal-containing silica particles in order to inhibit uptake by phagocytes in vivo. Metal nanoparticles and silica particles without surface modification are recognized as foreign bodies by phagocytes in vivo and are therefore easily taken up by the reticuloendothelial system, such as the liver and spleen, due to the opsonization effect. To prevent this, the surface-modified metal-containing silica particles of the present invention have polyethylene glycol chains present on their surface by chemical or electrostatic bonding. Silica particles without polyethylene glycol chains have a high adhesion amount of plasma proteins to the silica particle surface, which facilitates the opsonization effect, resulting in rapid transport of the silica particles to the pancreas and spleen and shortened imaging times. In contrast, the surface-modified metal-containing silica particles of the present invention are metal-containing silica particles having polyethylene glycol chains on the particle surface, so that adhesion of plasma proteins to the silica particle surface is reduced, and the opsonization effect can be suppressed, so that the transport of silica particles to the pancreas or spleen can be suppressed, and the imaging time can be extended.Furthermore, the surface-modified metal-containing silica particles of the present invention have polyethylene glycol chains on the particle surface, which prevents aggregation of the metal-containing silica particles in the body and suppresses unintended protein adsorption to the metal-containing silica particle surface.

[0051] The surface-modified metal-containing silica particles of the first embodiment of the present invention are silica particles, which contain a plurality of biocompatible molecule-modified metal nanoparticles in the interior of particles, which are Au nanoparticles or Pt nanoparticles surface-modified with biocompatible molecules having thiol groups and amino groups and / or carboxyl groups, and whose particle surface is chemically modified with a surface modifier having polyethylene glycol chains.The surface-modified metal-containing silica particles of the first embodiment of the present invention can be exemplified by: the silanol groups present on the surface of silica particles are directly chemically reacted with a surface modifier having polyethylene glycol chains to bond the polyethylene glycol chains; or the silanol groups present on the surface of silica particles are first chemically reacted with a surface modifier for bonding the polyethylene glycol chains to be surface-modified, and then the surface modifier having polyethylene glycol chains is chemically reacted with the surface modifier having polyethylene glycol chains to bond the polyethylene glycol chains to the surface-modified groups.

[0052] For example, the surface-modified metal-containing silica particles of the first form of the present invention can be obtained by chemically modifying metal-containing silica particles containing multiple biocompatible molecule-modified metal nanoparticles inside the particles, in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, using a polyethylene glycol-terminated silane coupling agent (Si-PEG) to perform polyethylene glycol modification of the metal-containing silica particles (hereinafter also referred to as modified PEG modification). The surface-modified metal-containing silica particles of the first embodiment of the present invention are prepared by first reacting a metal-containing silica particle containing a plurality of biocompatible molecule-modified metal nanoparticles inside the particle, the surface of which has been modified with a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group, with an amino group modifier such as (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, 3-(2-aminoethyl)aminopropylmethoxysilane, 3-(2-aminoethyl)aminopropylethoxysilane, aminopropyldimethoxysilane, aminopropylmethyldiethoxysilane, aminobutyltriethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-(2-aminoethylamino)octyltrimethoxysilane, 4-aminobutyltriethoxysilane, or 4-aminobutyltrimethoxysilane, to form a silica nanoparticle. The surface of the particles is modified with amino groups, and then the amino groups introduced onto the surface of the silica particles are reacted with a surface modifying agent having a polyethylene glycol chain such as α-mercaptoethyl-ω-methoxypolyoxyethylene or O-(3-carboxypropyl)-O'-[2-(3-mercaptopropionylamino)ethyl]polyethylene glycol; in other words, a polyethylene glycol derivative having a carboxyl group at the end, a polyethylene glycol derivative having a hydroxyl group at the end, a polyethylene glycol derivative having a thiol group at the end, a polyethylene glycol derivative having a phosphate group at the end, or a polyethylene glycol derivative having a sulfo group at the end, to chemically modify the particles and thereby perform PEG modification of the metal-containing silica particles.

[0053] The surface-modified metal-containing silica particles of the second embodiment of the present invention are silica particles that contain a plurality of biocompatible molecule-modified metal nanoparticles inside the particles, which are Au or Pt nanoparticles surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, and have PEG-modified metal nanoparticles, which are Au or Pt nanoparticles surface-modified with a surface modifier having a polyethylene glycol chain, electrostatically adsorbed to the particle surface.The surface-modified metal-containing silica particles of the second embodiment of the present invention can have Au or Pt nanoparticles present not only inside the Au or Pt-containing silica particles but also on the surface of the metal-containing silica particles, thereby increasing the Au or Pt content of the surface-modified metal-containing silica particles and further improving the X-ray contrast ability.

[0054] In the surface-modified metal-containing silica particles of the second embodiment of the present invention, the particle diameter of the Au nanoparticles or Pt nanoparticles (metal nanoparticles) electrostatically adsorbed to the surface of the metal-containing silica particles is preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, more preferably 7 nm or less, and more preferably 1 to 5 nm. For example, when Au nanoparticles or Pt nanoparticles are used in vivo as a contrast agent or drug delivery system, the metal nanoparticles must be excreted from the body after use. When the particle diameter of the metal nanoparticles electrostatically adsorbed to the surface of the metal-containing silica particles is within the above range, they can easily pass through the glomerular basement membrane of the kidney, enabling them to be excreted from the body.

[0055] For example, metal-containing silica particles containing a plurality of biocompatible molecule-modified metal nanoparticles, in which Au or Pt nanoparticles are surface-modified with biocompatible molecules having thiol groups and amino and / or carboxyl groups, have a negative charge on the particle surface. Taking advantage of this, the surface-modified metal-containing silica particles of the second embodiment of the present invention can be obtained by the following method. First, a positively charged cationic polymer, such as polydiallyldimethylammonium chloride (PDADMAC), is adsorbed onto the negatively charged metal-containing silica particles. Next, Au or Pt nanoparticles are contacted with the metal-containing silica particles whose surfaces have been modified with PDADMAC, and the Au or Pt nanoparticles (metal nanoparticles) are adsorbed onto the metal-containing silica particles whose surfaces have been modified with PDADMAC through electrostatic interaction. Next, the metal-containing silica particles whose surfaces have been modified with PDADMAC are contacted with a surface modifier having a polyethylene glycol chain, thereby reacting the surface modifier having a polyethylene glycol chain with the metal nanoparticles present on the surface of the silica particles, and introducing the polyethylene glycol chain onto the surface of the silica particles via the metal nanoparticles. Surface modifiers having polyethylene glycol chains that can be used to modify the surface of metal nanoparticles include polyethylene glycols having terminal thiol groups, such as α-mercaptoethyl-ω-methoxypolyoxyethylene and poly(ethylene glycol) methyl ether thiol. Cyclic polyethylene glycols can also be used. Biocompatible cyclic polymers such as cyclic polyethylene glycols can improve the stability of metal nanoparticles, even at high and low temperatures and under physiological conditions.

[0056] Alternatively, the surface-modified metal-containing silica particles of the second embodiment of the present invention can be obtained by the following method. First, the surface of negatively charged metal-containing silica particles is modified with a positively charged cationic silane coupling agent, such as 3-aminopropyltriethoxysilane (APTES) or 3-aminopropyltrimethoxysilane (APTMS). Next, Au nanoparticles or Pt nanoparticles are contacted with the metal-containing silica particles whose surfaces have been modified with APTES or APTMS, and the Au nanoparticles or Pt nanoparticles (metal nanoparticles) are adsorbed onto the metal-containing silica particles whose surfaces have been modified with APTES or APTMS through electrostatic interaction. Next, the metal-containing silica particles whose surfaces have been modified with APTES or APTMS are contacted with a surface modifier having a polyethylene glycol chain, thereby reacting the surface modifier having a polyethylene glycol chain with the metal nanoparticles present on the surface of the silica particles, and introducing the polyethylene glycol chain onto the surface of the silica particles via the metal nanoparticles. Examples of surface modifiers having a polyethylene glycol chain that can be used to modify the surface of metal nanoparticles include polyethylene glycols having a thiol group at the end, such as α-mercaptoethyl-ω-methoxypolyoxyethylene and poly(ethylene glycol) methyl ether thiol. Cyclic polyethylene glycols can also be used.

[0057] The particle diameter of the surface-modified metal-containing silica particles of the present invention is preferably greater than 15 nm and less than 1 μm, more preferably greater than 20 nm and less than 500 nm. When the particle diameter of the surface-modified metal-containing silica particles of the present invention is within this range, the particles can be observed over time due to improved retention in blood, and the particle diameter is sufficiently small compared with the diameter of capillaries (e.g., 8 μm), making the silica particles applicable to a wide range of diagnoses.

[0058] The surface-modified metal-containing silica particles of the present invention can be spherical. Particles with a large aspect ratio tend to pierce biological tissue and cause inflammation. When silica is produced in a liquid phase, it is amorphous and therefore tends to assume a spherical shape, thereby minimizing tissue damage. The aspect ratio of the surface-modified metal-containing silica particles of the present invention is preferably 5 or less, more preferably 4 or less, and even more preferably 3.5 or less.

[0059] In the present invention, the particle diameter of the "biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group" contained within the surface-modified metal-containing silica particles is determined by measuring the minor axis of 100 arbitrarily selected metal nanoparticles in a TEM image obtained using a transmission electron microscope (TEM) (JEM-2100, manufactured by JEOL Ltd.) at an accelerating voltage of 200 kV, and averaging the obtained values.

[0060] In the present invention, in the surface-modified metal-containing silica particles of the second form of the present invention, the particle diameter of the metal nanoparticles electrostatically adsorbed to the surface of the silica particles is the average value obtained by measuring the minor axis diameter of 100 arbitrarily selected metal nanoparticles in a TEM image obtained using a transmission electron microscope (TEM) (JEM-2100, manufactured by JEOL Ltd.) at an accelerating voltage of 200 kV.

[0061] In the present invention, the particle diameter of the surface-modified metal-containing silica particles of the present invention is determined by measuring the minor axis diameter of 100 arbitrarily selected surface-modified metal-containing silica particles in a TEM image obtained using a transmission electron microscope (TEM) (JEM-2100, manufactured by JEOL Ltd.) at an acceleration voltage of 200 kV, and averaging the obtained values.

[0062] The surface-modified metal-containing silica particles of the present invention are suitable for use as silica particles for contrast agents in X-ray CT examinations.

[0063] The contrast agent of the present invention is characterized by containing the surface-modified metal-containing silica particles of the present invention.

[0064] The surface-modified metal-containing silica particles of the present invention can be used not only as contrast agents but also as biomarkers, microcapsules, biosensors, vascular contrast agents, urinary tract contrast agents, lymph node contrast agents, markers for radiation therapy, catalysts, biomarkers, dyes, carriers, drug delivery particles, photoacoustic imaging materials, spectroscopic tags, photonics applications, and the like.

[0065] The method for producing metal-containing silica particles of the present invention includes the steps of: preparing a reaction raw material solution by adding tetraalkoxysilane or a derivative thereof to a colloidal solution containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material solution; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; The present invention relates to a method for producing metal-containing silica particles, characterized by comprising the steps of:

[0066] The method for producing metal-containing silica particles of the present invention includes a reaction raw material liquid preparation step and a metal-containing silica particle production step.

[0067] The reaction raw material liquid preparation step in the method for producing metal-containing silica particles of the present invention is a step of adding tetraalkoxysilane or a derivative thereof to a colloidal liquid containing biocompatible molecule-modified metal nanoparticles to obtain a reaction raw material liquid.

[0068] The biocompatible molecule-modified metal nanoparticles used in the reaction raw material solution preparation step are metal nanoparticles in which Au or Pt nanoparticles have been surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group. The biocompatible molecule-modified metal nanoparticles are formed by reacting the Au or Pt on the particle surface of the Au or Pt nanoparticles with the thiol group of a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group. In other words, the biocompatible molecule-modified metal nanoparticles consist of Au or Pt nanoparticles and reaction residues of biocompatible molecules having a thiol group and an amino group and / or a carboxyl group that are bound to the surface of the Au or Pt nanoparticles.

[0069] The method for producing biocompatible molecule-modified metal nanoparticles used in the reaction raw material solution preparation step is not particularly limited, but examples include a method in which, in the presence of biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, a metal salt (Au salt or Pt salt) is reduced with a reducing agent using a metal ion (Au ion or Pt ion) reducing agent and alkali to reduce the metal ion and generate Au nanoparticles or Pt nanoparticles, and then a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group is reacted with the Au or Pt on the surface of the generated Au nanoparticles or Pt nanoparticles.

[0070] Biocompatible molecules having a thiol group and an amino group and / or a carboxyl group have a thiol group, an amino group, and a carboxyl group within the molecule, or a thiol group and an amino group, or a thiol group and a carboxyl group, and are biocompatible. Biocompatible molecules having a thiol group and an amino group and / or a carboxyl group contribute to reducing the particle size of metal nanoparticles and improving their dispersibility during production. Examples of biocompatible molecules having a thiol group and an amino group and / or a carboxyl group include compounds selected from the group consisting of glutathione (GSH), cysteine, cysteamine, polyethylene glycol having an amino group at one end of the polyethylene glycol chain and a thiol group at the other end (NH-PEG(polyethylene glycol)-SH), and polyethylene glycol having a carboxyl group at one end of the polyethylene glycol chain and a thiol group at the other end (COOH-PEG(polyethylene glycol)-SH). Among these, glutathione is preferred as a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group because it is abundantly present in the body and has high biocompatibility. Metal salts include HAuCl4 and its hydrate, NaAuCl4 and its hydrate, KAuCl4 and its hydrate, gold hydroxide (III) Au(OH)3, digold trioxide Au2O3, digold trisulfide Au2S3, gold chloride (III) AuCl3, gold chloride (I) AuCl, ammonium tetrachloroaurate or its hydrate, lithium tetrachloroaurate or its hydrate, gold iodide, gold bromide, gold acetate, platinum oxide, platinum chloride, platinum bromide, platinum iodide, hexachloroplatinic (IV) acid and its hydrate, hexachloroplatinic (IV) acid and its hydrate, and hexachloroplatinic (IV) acid and its hydrate. Examples include sodium gold(IV) and its hydrate, potassium hexachloroplatinate(IV), sodium tetrachloroplatinate(II) and its hydrate, potassium tetrachloroplatinate(II), ammonium hexabromoplatinate(IV), potassium tetrabromoplatinate(II), potassium hexaiodoplatinate(IV), ammonium tetrachloroplatinate(II), dihydrogen hexahydroxyplatinate(IV), sodium hexahydroxyplatinate(IV), and tetraamineplatinum(II) hydroxide.Examples of reducing agents for reducing metal salts include tetrakis(hydroxymethyl)phosphonium chloride, sodium borohydride, citric acid and its salts, citric acid hydrate, hydrazine and its salts, borohydride salts, sulfate, thiosulfate, tartrate, phosphinic acid and its salts, formic acid and its salts, acetic acid and its salts, propionic acid and its salts, oxalic acid and its salts, ascorbic acid and its salts, phosphoric acid and its salts, hypophosphorous acid and its salts (e.g., sodium hypophosphite (NaH2PO2)), transition metal salts, glycine, dimethylamine borane, fructose, glycerol, acetaldehyde, glucose, cellulose, carboxymethyl cellulose, formaldehyde, ascorbic acid, and sugar decomposition products. Examples of the alkali used together with the reducing agent for reducing the metal salt include sodium hydroxide, potassium hydroxide, ammonia, sodium hydrogen carbonate, calcium hydroxide, methylamine, dimethylamine, ethylenediamine, ethylenediaminetetraacetic acid and its sodium salt, diethylenetriamine, trimethylamine, triethylamine, N-ethyldiisopropylamine, tri-n-propylamine, triisopropylamine, triethanolamine, tripropanolamine, dimethylethanolamine, arginine, lysine, 3-ethoxypropylamine, and inorganic ammonium compounds.

[0071] When a metal salt is reduced with a metal ion reducing agent and alkali in the presence of a biocompatible molecule having a thiol group and an amino group and / or a carboxyl group, the ratio of the number of moles of the biocompatible molecule having a thiol group and an amino group and / or a carboxyl group to the number of moles of the metal in atomic terms of the metal salt is preferably 1:200 to 200: 1, more preferably 1:100 to 100: 1. The reduction reaction temperature is preferably 0 to 100°C, more preferably 5 to 95°C, and the reduction reaction time is preferably 0 to 120 hours, more preferably 0 to 72 hours.

[0072] When surface-modified metal-containing silica particles are used as a material for a contrast agent, in order to efficiently exhibit the properties, it is important to control the dispersion and aggregation of metal nanoparticles when producing the metal-containing silica particles. In the method for producing metal-containing silica particles of the present invention and the method for producing surface-modified metal-containing silica particles of the present invention described below, the surface of the metal nanoparticles is chemically modified with the above-mentioned biocompatible molecules in order to improve the dispersibility of the metal nanoparticles in various solvents. This prevents the aggregation of the metal nanoparticles, improves their affinity to the solvent, and can also cause steric hindrance and electrostatic interactions between the particles, thereby improving the dispersibility.

[0073] The particle size of the biocompatible molecule-modified metal nanoparticles used in the reaction raw material solution preparation step is preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, and more preferably 1 to 5 nm. For example, when metal nanoparticles are used in vivo as contrast agents or drug delivery systems, the metal nanoparticles must be excreted from the body after use. When the particle size of the biocompatible molecule-modified metal nanoparticles is within the above range, they can easily pass through the glomerular basement membrane of the kidney, enabling them to be excreted from the body.

[0074] The tetraalkoxysilane used in the reaction raw material solution preparation step is not particularly limited, and examples thereof include tetraalkoxysilanes represented by the following general formula (1): Si(OR 1 )4(1) In the general formula (1), R 1 may be the same or different. 1 is an alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms. 1 Specifically, R includes a methyl group, an ethyl group, a propyl group, an isobutyl group, a butyl group, a pentyl group, and a hexyl group. The tetraalkoxysilane represented by the general formula (1) is advantageous in that it can provide a dense shell. 1 Tetramethoxysilane (TMOS), where R is a methyl group1 Tetraethoxysilane (TEOS), in which ⁢ ...

[0075] In the reaction raw material solution preparation step, the amount of tetraalkoxysilane or its derivative added is such that the ratio of the number of moles of tetraalkoxysilane or its derivative to the number of moles of Au or Pt in atomic terms in the biocompatible molecule-modified metal nanoparticles (number of moles of tetraalkoxysilane or its derivative / number of moles of Au or Pt in atomic terms) is preferably 1:1000 to 1000:1, more preferably 1:500 to 500:1. By adding the amount of tetraalkoxysilane or its derivative within this range, the content of Au or Pt in the metal-containing silica particles becomes appropriate for performing good diagnostic imaging, for example, in X-ray CT scans. When multiple tetraalkoxysilanes or their derivatives are used, the number of moles of the tetraalkoxysilanes or their derivatives referred to above refers to the total number of moles.

[0076] In the reaction raw material solution preparation step, the concentration of the biocompatible molecule-modified metal nanoparticles in the colloidal solution is not particularly limited, but is preferably 0.001 to 50% by mass, more preferably 0.005 to 25% by mass. When the concentration of the biocompatible molecule-modified metal nanoparticles in the colloidal solution is within the above range, the Au or Pt content in the metal-containing silica particles becomes an appropriate content for performing good image diagnosis, for example, in X-ray CT examinations.

[0077] When a tetraalkoxysilane or a derivative thereof is added as an alcohol solution in the reaction raw material solution preparation step, the concentration of the tetraalkoxysilane or a derivative thereof in the alcohol solution is not particularly limited, but is preferably 0.001 to 100% by mass, more preferably 0.01 to 50% by mass. When the concentration of the tetraalkoxysilane or a derivative thereof in the alcohol solution is within the above range, the Au or Pt content in the metal-containing silica particles becomes an appropriate content for performing good image diagnosis, for example, in X-ray CT examinations. Note that when multiple tetraalkoxysilanes or derivatives thereof are used, the above concentration of the tetraalkoxysilanes or derivatives thereof refers to the total mass of the tetraalkoxysilanes or derivatives thereof in the alcohol solution.

[0078] In the reaction raw material solution preparation step, tetraalkoxysilane or its derivative is added to a colloidal solution in which biocompatible molecule-modified metal nanoparticles, in which Au or Pt nanoparticles are surface-modified with biocompatible molecules having thiol groups and amino or carboxyl groups, are dispersed in an aqueous dispersion medium, and the colloidal solution is stirred appropriately to obtain a reaction raw material solution. At this time, the temperature of the colloidal solution and the reaction raw material solution is preferably 0 to 100°C.

[0079] The metal-containing silica particle production step in the method for producing metal-containing silica particles of the present invention is a step of adding an alkali catalyst to the reaction raw material liquid and hydrolyzing and polycondensing tetraalkoxysilane or a derivative thereof to obtain a colloidal solution of metal-containing silica particles.

[0080] The alkali catalyst used in the metal-containing silica particle production step is not particularly limited as long as it is one that is normally used in the hydrolysis and polycondensation of tetraalkoxysilane, and examples thereof include sodium hydroxide, ammonia, 3-ethoxypropylamine, potassium hydroxide, calcium bicarbonate, calcium hydroxide, methylamine, dimethylamine, ethylenediamine, ethylenediaminetetraacetic acid and its sodium salt, diethylenetriamine, arginine, lysine, etc. Of these, sodium hydroxide is preferred as the alkali catalyst in terms of cytotoxicity, biocompatibility, cost, etc.

[0081] In the metal-containing silica particle production step, the catalyst concentration in the reaction solution is preferably 0.0001 to 20.0% by mass, more preferably 0.0001 to 15.0% by mass. By keeping the catalyst concentration in the reaction solution within this range, it becomes easier to obtain metal-containing silica particles that contain biocompatible molecule-modified metal nanoparticles in an appropriate state within the particles, and to obtain silica particles with a particle size that allows for time-dependent observation due to improved blood retention, for example, silica particles that are preferably greater than 15 nm and 1 μm or less, more preferably 20 nm to 500 nm.

[0082] In the metal-containing silica particle production process, a reaction solution containing biocompatible molecule-modified metal nanoparticles, tetraalkoxysilane or a derivative thereof, and an alkali catalyst is appropriately stirred to carry out hydrolysis and polycondensation of the tetraalkoxysilane or a derivative thereof. The hydrolysis and polycondensation reactions of the tetraalkoxysilane or a derivative thereof in the metal-containing silica particle production process are as described above. The reaction temperature during the hydrolysis and polycondensation of the tetraalkoxysilane or a derivative thereof in the metal-containing silica particle production process is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, the reaction time during the hydrolysis and polycondensation of the tetraalkoxysilane or a derivative thereof in the metal-containing silica particle production process is preferably 0 to 1500 minutes, more preferably 0 to 1000 minutes.

[0083] The inventors speculate that the hydrolysis and polycondensation of tetraalkoxysilane or its derivative in the metal-containing silica particle production process produces metal-containing silica particles as follows: First, hydrolysis of the tetraalkoxysilane or its derivative occurs. Next, the hydroxyl groups generated by the hydrolysis of the tetraalkoxysilane or its derivative react with or bond to amino or carboxyl groups of the reactive residues of the biocompatible molecules present on the surface of the biocompatible molecule-modified metal nanoparticles, either through reaction or some other interaction, resulting in the formation of a silylalkoxide or its derivative around the metal nanoparticles via the reactive residues of the biocompatible molecules. Next, multiple metal nanoparticles with the silylalkoxide or its derivative present around the metal nanoparticles are aggregated. Next, polycondensation of the silylalkoxide or its derivative around the metal nanoparticles occurs in a state where multiple metal nanoparticles with the silylalkoxide or its derivative present around the metal nanoparticles are aggregated. Next, hydrolysis and polycondensation of the tetraalkoxysilane or its derivative proceed around the aggregates of multiple metal nanoparticles, causing silica particles to grow and producing metal-containing silica particles.

[0084] As described above, it is believed that in the early stage of silica particle production, aggregates of metal nanoparticles with silyl alkoxide layers formed thereon are formed around the metal nanoparticles, and then hydrolysis and polycondensation of tetraalkoxysilane or its derivatives proceeds around the aggregates, resulting in the growth of silica particles. As a result, the metal nanoparticles within the metal-containing silica particles are present in a state where they are not aggregated but are closely packed together at high density. For example, in X-ray CT examination, the X-ray absorption value per unit concentration is improved, and when the silica particles are decomposed, the metal nanoparticles are easily released without being aggregated. Note that the presence of the metal nanoparticles within the metal-containing silica particles in a state where they are not aggregated but are closely packed together is confirmed by observation with a transmission electron microscope.

[0085] In the method for producing metal-containing silica particles of the present invention, a colloidal solution of metal-containing silica particles is obtained by carrying out a metal-containing silica particle generation process, which contains multiple biocompatible molecule-modified metal nanoparticles inside the particles, the nanoparticles having their surfaces modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group.

[0086] The particle size of the biocompatible molecule-modified metal-containing silica particles obtained by carrying out the metal-containing silica particle production step is preferably greater than 15 nm and equal to or less than 1 μm, more preferably equal to or greater than 20 nm and equal to or less than 500 nm.

[0087] In the method for producing metal-containing silica particles of the present invention, the colloidal solution of biocompatible molecule modified metal-containing silica particles obtained by carrying out metal-containing silica particle production step is used, and if necessary, it is purified, dried, dialyzed, concentrated, diluted, dispersed, filtered, etc., to obtain the biocompatible molecule modified metal-containing silica particles in the state according to the intended use.In addition, in the method for producing metal-containing silica particles of the present invention, the colloidal solution of biocompatible molecule modified metal-containing silica particles obtained by carrying out metal-containing silica particle production step is purified if necessary, and can also be used as the colloidal solution of metal-containing silica particles that is involved in the method for producing surface-modified metal-containing silica particles of the present invention.

[0088] Applications of the metal-containing silica particles obtained by the method for producing metal-containing silica particles of the present invention, i.e., biocompatible molecule-modified metal-containing silica particles whose surface is modified with a biocompatible molecule having a thiol group and an amino group or a carboxyl group, include, for example, vascular contrast agents, urinary tract contrast agents, lymph node contrast agents, radiotherapy markers, catalysts, biomarkers, dyes, carriers, drug delivery particles, photoacoustic imaging materials, spectroscopic tags, and photonics applications.

[0089] The method for producing surface-modified metal-containing silica particles of the present invention includes the steps of: preparing a reaction raw material liquid by adding tetraalkoxysilane or a derivative thereof to a colloidal liquid containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material liquid; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; a biocompatible molecular chain introduction step of introducing biocompatible molecular chains into the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; The present invention relates to a method for producing surface-modified metal-containing silica particles, characterized by having the following:

[0090] The reaction raw material solution preparation step and metal-containing silica particle production step in the method for producing surface-modified metal-containing silica particles of the present invention are the same as the reaction raw material solution preparation step and metal-containing silica particle production step in the method for producing metal-containing silica particles of the present invention.

[0091] The biocompatible molecular chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention is a step of introducing biocompatible molecular chains into metal-containing silica particles obtained by carrying out the reaction raw material solution preparation step and the metal-containing silica particle production step, thereby obtaining a colloidal solution of surface-modified metal-containing silica particles in which biocompatible molecular chains are present on the particle surfaces of the metal-containing silica particles, i.e., on the particle surfaces of silica particles containing multiple biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group.

[0092] In the biocompatible molecular chain introduction step, the biocompatible molecular chain to be introduced onto the particle surface of the metal-containing silica particles is not particularly limited as long as it is biocompatible, and examples thereof include polyethylene glycol chains, hyaluronic acid, polyvinyl alcohol, cyclodextrin, alginic acid, alginate salts, lactic acid-glycolic acid copolymer polyglycolide, poly-L-lactide, poly-D,L-lactide, poly(lactide-co-glycolide), polypropylene glycol, ethylene glycol-propylene glycol copolymer, polyoxyethylated polyol, polysaccharide, dextran, polyvinyl ethyl ether, chitin, chitosan, oligonucleotides, biodegradable polymers, lipid polymers, and polypeptides.

[0093] In the biocompatible molecular chain introduction step, the method for introducing biocompatible molecular chains onto the surface of the metal-containing silica particles is not particularly limited, and examples thereof include a method of chemically modifying the surface of the metal-containing silica particles with a surface modifier containing biocompatible molecular chains, a method of adsorbing biocompatible molecular chains through electrostatic interaction, a method of adsorbing biocompatible molecular chains through hydrogen bonding and / or intermolecular forces, a method of supporting biocompatible molecular chains in pores on the surface of the silica particles, and a method of surface-modifying the surface of the silica particles and chemically modifying and / or adsorbing biocompatible molecular chains to the introduced functional groups.

[0094] The biocompatible molecular chain introduction step may include a polyethylene glycol chain introduction step in which a polyethylene glycol chain is introduced into metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles.

[0095] The polyethylene glycol chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention is a step of introducing polyethylene glycol chains into metal-containing silica particles obtained by carrying out the reaction raw material solution preparation step and the metal-containing silica particle production step, thereby obtaining a colloidal solution of surface-modified metal-containing silica particles in which polyethylene glycol chains are present on the particle surfaces of the metal-containing silica particles, i.e., on the particle surfaces of silica particles containing multiple biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group.

[0096] The polyethylene glycol chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention is not particularly limited as long as it is a method that can introduce polyethylene glycol chains onto the surfaces of silica particles.

[0097] In a first embodiment of the polyethylene glycol chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention, at least an amino group-modified metal-containing silica particle producing step of adding an amino group modifying agent to a colloidal solution of metal-containing silica particles obtained by carrying out the reaction raw material solution preparing step and the metal-containing silica particle producing step to obtain a colloidal solution of amino group-modified metal-containing silica particles; a surface-modified metal-containing silica particle producing step of adding a surface modifier having a polyethylene glycol chain to the colloidal solution of the amino group-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; The process includes the steps of:

[0098] The amino group-modified metal-containing silica particle production step according to the first embodiment of the polyethylene glycol chain introduction step is a step of adding an amino group modifying agent to a colloidal solution of metal-containing silica particles to obtain a colloidal solution of amino group-modified metal-containing silica particles.

[0099] The amino group modifying agent used in the amino group-modified metal-containing silica particle generating step is not particularly limited as long as it is a surface modifying agent having an amino group and is a compound that can react with the silanol groups present on the surface of the silica particles to introduce the reaction residue having an amino group, which is the reaction residue, into the silica particles. Examples of the amino group modifying agent include (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, (aminoethyl)aminopropylmethoxysilane, aminopropyldimethoxysilane, aminopropylmethyldiethoxysilane, aminobutyltriethoxysilane, etc.

[0100] In the amino group-modified metal-containing silica particle production step, the site of the amino group introduced into the metal-containing silica particles by amino group modification becomes the site to which the polyethylene glycol chain is introduced, so the amount of amino group modifying agent added is appropriately adjusted so that the amount of polyethylene glycol chain introduced into the metal-containing silica particles is such that the effect of the polyethylene glycol chain of the present invention is exerted. The amount of amino group modifying agent added is preferably 1 to 5000 parts by mass, more preferably 1 to 2500 parts by mass, relative to 100 parts by mass of the metal-containing silica particles.

[0101] In the amino group-modified metal-containing silica particle production step, a reaction solution containing metal-containing silica particles and an amino group modifier is appropriately stirred to react the metal-containing silica particles with the amino group modifier, thereby modifying the metal-containing silica particles with amino groups. In the amino group-modified metal-containing silica particle production step, the reaction temperature during amino group modification is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, in the amino group-modified metal-containing silica particle production step, the reaction time during amino group modification is preferably 0 to 1500 minutes, more preferably 0 to 1000 minutes.

[0102] By carrying out the amino group-modified metal-containing silica particle producing step, a colloidal solution of amino group-modified metal-containing silica particles, in which amino groups are introduced onto the surfaces of the metal-containing silica particles, can be obtained.

[0103] The surface-modified metal-containing silica particle production step (1) according to the first embodiment of the polyethylene glycol chain introduction step is a step of adding a surface modifier having a polyethylene glycol chain to a colloidal solution of amino group-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles.

[0104] The surface modifier having a polyethylene glycol chain used in the surface-modified metal-containing silica particle production step (1) is not particularly limited as long as it is a compound that has a polyethylene glycol chain and can react with amino groups present on the surface of silica particles to introduce a reactive residue having a polyethylene glycol chain, which is the reactive residue, into the silica particles. Examples of surface modifiers having a polyethylene glycol chain include α-mercaptoethyl-ω-methoxypolyoxyethylene, O-(3-carboxypropyl)-O'-[2-(3-mercaptopropionylamino)ethyl]polyethylene glycol, in other words, polyethylene glycol derivatives having a terminal carboxyl group, polyethylene glycol derivatives having a terminal hydroxyl group, polyethylene glycol derivatives having a terminal thiol group, polyethylene glycol derivatives having a terminal phosphate group, and polyethylene glycol derivatives having a terminal sulfo group.

[0105] In the surface-modified metal-containing silica particle production step (1), the site of the amino group introduced into the metal-containing silica particle by amino group modification becomes the site to which the polyethylene glycol chain is introduced. Therefore, the amount of the surface modifier having the polyethylene glycol chain added is preferably 0.1 to 5000 parts by mass, more preferably 0.1 to 2500 parts by mass, per 100 parts by mass of the amino group modifier.

[0106] In the surface-modified metal-containing silica particle production step (1), a reaction solution containing amino-group-modified metal-containing silica particles and a surface modifier having a polyethylene glycol chain is appropriately stirred to react the amino-group-modified metal-containing silica particles with the surface modifier having a polyethylene glycol chain, thereby modifying the metal-containing silica particles with polyethylene glycol. In the surface-modified metal-containing silica particle production step (1), the reaction temperature during polyethylene glycol modification is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, in the surface-modified metal-containing silica particle production step (1), the reaction time during polyethylene glycol modification is preferably 0 to 1500 minutes, more preferably 0 to 1000 minutes.

[0107] By carrying out the surface-modified metal-containing silica particle producing step (1), a colloidal solution of surface-modified metal-containing silica particles is obtained, in which polyethylene glycol chains are introduced onto the surfaces of the metal-containing silica particles.

[0108] As a second embodiment of the polyethylene glycol chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention, at least a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to a colloidal solution of metal-containing silica particles obtained by the reaction raw material solution preparing step and the metal-containing silica particle producing step to obtain a colloidal solution of cationic polymer-modified metal-containing silica particles; a surface-modified metal-containing silica particle production step in which Au nanoparticles or Pt nanoparticles are added as metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles, and then a surface modifier having a polyethylene glycol chain is added to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; The process includes the steps of:

[0109] The cationic polymer-modified metal-containing silica particle production step according to the second embodiment of the polyethylene glycol chain introduction step is a step of adding a cationic polymer to a colloidal solution of metal-containing silica particles to obtain a colloidal solution of cationic polymer-modified metal-containing silica particles.

[0110] The cationic polymer used in the cationic polymer-modified metal-containing silica particle production process is not particularly limited as long as it has cations such as amino groups in its molecular chain and can adsorb to the surface of negatively charged silica particles through electrostatic interaction. Examples of cationic polymers include polydiallyldimethylammonium chloride (PDADMAC), polyethyleneimine, chitosan, polylysine, vinylpyrrolidone-NN-dimethylaminoethyl methacrylic acid copolymer diethyl sulfate, alkylamine-epichlorohydrin condensates, polyethyleneimine, alkylene dichloride-polyalkylenepolyamine condensates, dicyandichloride-polyalkylenepolyamine condensates, polydimethylaminoethyl methacrylate, polydiallyldimethylammonium chloride, copolymers of acrylamide and diallyldimethylammonium chloride, copolymers of acrylamide and acryloyloxyethyl compounds containing quaternary ammonium salts, polymers of acrylates, methacrylates, acrylamides, etc., with quaternary ammonium bases, and diallyldimethylammonium chloride polymers. The cationic polymer can be used, for example, in the form of a suspension in which the cationic polymer is dispersed in an aqueous dispersion medium.

[0111] In the cationic polymer-modified metal-containing silica particle production step, the amount of cationic polymer added is adjusted as appropriate, but is preferably 1 to 10,000 parts by mass, more preferably 1 to 5,000 parts by mass, per 100 parts by mass of the metal-containing silica particles.

[0112] In the cationic polymer-modified metal-containing silica particle production process, a reaction solution containing metal-containing silica particles and a cationic polymer is appropriately stirred to cause the cationic polymer to be adsorbed onto the metal-containing silica particles through electrostatic interaction, thereby modifying the metal-containing silica particles with the cationic polymer. In the cationic polymer-modified metal-containing silica particle production process, the reaction temperature during the cationic polymer modification is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, in the cationic polymer-modified metal-containing silica particle production process, the reaction time during the cationic polymer modification is preferably 0 to 1500 minutes, more preferably 0 to 1000 minutes.

[0113] By carrying out the cationic polymer modified metal-containing silica particle producing step, a colloidal solution of cationic polymer modified metal-containing silica particles can be obtained.

[0114] The surface-modified metal-containing silica particle production step (2), which is a second embodiment of the polyethylene glycol chain introduction step, is a step in which Au nanoparticles or Pt nanoparticles are first added as metal nanoparticles to a colloidal solution of cationic polymer-modified metal-containing silica particles, and then a surface modifier having a polyethylene glycol chain is added to obtain a colloidal solution of surface-modified metal-containing silica particles.

[0115] The Au nanoparticles or Pt nanoparticles (hereinafter collectively referred to as metal nanoparticles) used in the surface-modified metal-containing silica particle production process (2) are produced by physical pulverization of bulk metal or by a method of generating metal atoms and agglomerating them (agglomeration method). The agglomeration method can easily produce high-purity metal nanoparticles. Agglomeration methods are divided into dry and wet methods. Dry methods include CVD, which generates gold or platinum atoms by decomposing a precursor. Meanwhile, wet methods, which generate zero-valent metal atoms from a precursor in a liquid, utilize reduction from a metal salt or thermal decomposition of a metal complex. Wet methods often use reduction with alcohol, hydrazine, or organic acids.

[0116] The metal nanoparticles used in the surface-modified metal-containing silica particle production step (2) can be in the form of a dispersion of metal nanoparticles, an organic solvent dispersion of metal nanoparticles, or metal nanoparticle powder.

[0117] The particle diameter of the metal nanoparticles used in the surface-modified metal-containing silica particle production step (2) is preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, and more preferably 1 to 5 nm. For example, when metal nanoparticles are used in vivo as contrast agents or drug delivery systems, the metal nanoparticles must be excreted from the body after use. When the particle diameter of the metal nanoparticles used in the surface-modified metal-containing silica particle production step (2) is within the above range, they can easily pass through the glomerular basement membrane of the kidney, enabling them to be excreted from the body.

[0118] In the surface-modified metal-containing silica particle production step (2), metal nanoparticles are first adsorbed onto the cationic polymer-modified metal-containing silica particles. Since the adsorbed metal nanoparticles become the sites to which polyethylene glycol chains are introduced, the amount of metal nanoparticles added is preferably 0.01 to 1000 parts by mass, more preferably 0.01 to 500 parts by mass, per 100 parts by mass of the cationic polymer-modified metal-containing silica particles.

[0119] In the surface-modified metal-containing silica particle production step (2), a reaction solution containing cationic polymer-modified metal-containing silica particles and metal nanoparticles is appropriately stirred to adsorb Au nanoparticles or Pt nanoparticles onto the cationic polymer-modified metal-containing silica particles, thereby adsorbing the metal nanoparticles onto the metal-containing silica particles. In the surface-modified metal-containing silica particle production step (2), the temperature during metal nanoparticle adsorption is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, in the surface-modified metal-containing silica particle production step (2), the time during which the metal nanoparticles are adsorbed is preferably 0 to 1500 minutes, more preferably 0 to 1000 minutes.

[0120] By carrying out the surface-modified metal-containing silica particle producing step (2), a colloidal solution of metal-containing silica particles in which metal nanoparticles are adsorbed on the surfaces of the metal-containing silica particles is obtained.

[0121] In the surface-modified metal-containing silica particle production step (2), a surface modifier having a polyethylene glycol chain is then added to a colloidal solution of metal-containing silica particles having metal nanoparticles adsorbed on the surfaces of the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles.

[0122] The surface modifier having a polyethylene glycol chain used in the surface-modified metal-containing silica particle production step (2) is not particularly limited as long as it is a compound that has a polyethylene glycol chain and can react with the metal nanoparticles adsorbed on the surface of the silica particles to introduce a reactive residue having a polyethylene glycol chain, which is the reactive residue, into the metal nanoparticles adsorbed on the surface of the silica particles. Examples of the surface modifier having a polyethylene glycol chain include α-mercaptoethyl-ω-methoxypolyoxyethylene, O-(3-carboxypropyl)-O'-[2-(3-mercaptopropionylamino)ethyl]polyethylene glycol, in other words, polyethylene glycol derivatives having a terminal carboxyl group, polyethylene glycol derivatives having a terminal hydroxyl group, polyethylene glycol derivatives having a terminal thiol group, polyethylene glycol derivatives having a terminal phosphate group, and polyethylene glycol derivatives having a terminal sulfo group.

[0123] In the surface-modified metal-containing silica particle production step (2), the metal nanoparticles adsorbed on the surface of the metal-containing silica particles by metal nanoparticle adsorption become the sites to which polyethylene glycol chains are introduced. Therefore, the amount of the surface modifier having a polyethylene glycol chain added is preferably 0.1 to 5000 parts by mass, more preferably 0.1 to 2500 parts by mass, per 100 parts by mass of the metal nanoparticles.

[0124] In the surface-modified metal-containing silica particle production step (2), a reaction solution containing metal-containing silica particles having metal nanoparticles adsorbed on their surfaces and a surface modifier having polyethylene glycol chains is appropriately stirred to react the metal nanoparticles adsorbed on the surfaces of the metal-containing silica particles with the surface modifier having polyethylene glycol chains, thereby modifying the metal-containing silica particles with polyethylene glycol. In the surface-modified metal-containing silica particle production step (2), the reaction temperature during polyethylene glycol modification is preferably 0 to 100°C, more preferably 5 to 95°C. In addition, the reaction time during polyethylene glycol modification during the surface-modified metal-containing silica particle production step (2) is preferably 0 to 120 hours, more preferably 0 to 72 hours.

[0125] By carrying out the surface-modified metal-containing silica particle production step (2), a colloidal solution of surface-modified metal-containing silica particles is obtained, in which PEG-modified metal nanoparticles are electrostatically adsorbed onto the surface of cationic polymer-modified metal-containing silica particles, i.e., a colloidal solution of surface-modified metal-containing silica particles in which polyethylene glycol chains have been introduced onto the surface of the metal-containing silica particles.

[0126] As a third embodiment of the polyethylene glycol chain introduction step in the method for producing surface-modified metal-containing silica particles of the present invention, at least a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to a colloidal solution of metal-containing silica particles obtained by the reaction raw material solution preparing step and the metal-containing silica particle producing step to obtain a colloidal solution of cationic polymer-modified metal-containing silica particles; a PEG-modified metal nanoparticle generation step of adding a surface modifier having a polyethylene glycol chain to a solution containing Au nanoparticles or Pt nanoparticles as metal nanoparticles to generate PEG-modified metal nanoparticles; a surface-modified metal-containing silica particle producing step of adding the PEG-modified metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; The process includes the steps of:

[0127] The step of producing cationic polymer-modified metal-containing silica particles according to the third embodiment of the polyethylene glycol chain introduction step is the same as the step of producing cationic polymer-modified metal-containing silica particles according to the second embodiment.

[0128] The PEG-modified metal nanoparticle generation process according to the third embodiment of the polyethylene glycol chain introduction process is a process of adding a surface modifier having a polyethylene glycol chain to a liquid containing metal nanoparticles, which are Au nanoparticles or Pt nanoparticles, to generate PEG-modified metal nanoparticles.

[0129] The Au or Pt nanoparticles (metal nanoparticles) used in the PEG-modified metal nanoparticle production process are produced by physical crushing of bulk metal or by a method of generating metal atoms and agglomerating them (agglomeration method). The agglomeration method makes it easy to obtain highly pure metal nanoparticles. Agglomeration methods are divided into dry and wet methods. Dry methods include CVD, which generates gold or platinum atoms by decomposing a precursor. Meanwhile, wet methods, which generate zero-valent metal atoms from a precursor in a liquid, utilize reduction from a metal salt or thermal decomposition of a metal complex. Wet methods often use reduction with alcohol, hydrazine, or organic acids.

[0130] The metal nanoparticles used in the PEG-modified metal nanoparticle production step can be in the form of a metal nanoparticle dispersion, a metal nanoparticle organic solvent dispersion, or metal nanoparticle powder.

[0131] The particle size of the metal nanoparticles used in the PEG-modified metal nanoparticle production process is preferably 15 nm or less, more preferably 10 nm or less, more preferably 8 nm or less, and more preferably 1 to 5 nm. For example, when metal nanoparticles are used in vivo as contrast agents or drug delivery systems, the metal nanoparticles must be excreted from the body after use. When the particle size of the metal nanoparticles used in the PEG-modified metal nanoparticle production process is within the above range, they can easily pass through the glomerular basement membrane of the kidney, enabling them to be excreted from the body.

[0132] The surface modifier having a polyethylene glycol chain used in the PEG-modified metal nanoparticle production step is not particularly limited as long as it is a compound that has a polyethylene glycol chain and can react with Au nanoparticles or Pt nanoparticles to introduce a reaction residue having a polyethylene glycol chain, which is the reaction residue, into the Au nanoparticles or Pt nanoparticles. Examples of surface modifiers having a polyethylene glycol chain include α-mercaptoethyl-ω-methoxypolyoxyethylene, O-(3-carboxypropyl)-O'-[2-(3-mercaptopropionylamino)ethyl]polyethylene glycol, in other words, polyethylene glycol derivatives having a terminal carboxyl group, polyethylene glycol derivatives having a terminal hydroxyl group, polyethylene glycol derivatives having a terminal thiol group, polyethylene glycol derivatives having a terminal phosphate group, and polyethylene glycol derivatives having a terminal sulfo group.

[0133] In the PEG-modified metal nanoparticle production step, the amount of the surface modifier having a polyethylene glycol chain added is preferably 0.1 to 5000 parts by mass, more preferably 0.1 to 2500 parts by mass, per 100 parts by mass of the metal nanoparticles.

[0134] The surface-modified metal-containing silica particle production step (3), which is a third embodiment of the polyethylene glycol chain introduction step, is a step of adding PEG-modified metal nanoparticles to a colloidal solution of cationic polymer-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surface of the cationic polymer-modified metal-containing silica particles.

[0135] In the surface-modified metal-containing silica particle production step (3), the reaction solution containing the cationic polymer-modified metal-containing silica particles and the PEG-modified metal nanoparticles is appropriately stirred to adsorb the PEG-modified metal nanoparticles onto the cationic polymer-modified metal-containing silica particles, thereby adsorbing the metal nanoparticles onto the metal-containing silica particles. In the surface-modified metal-containing silica particle production step (3), the temperature during metal nanoparticle adsorption is preferably 0 to 100°C, more preferably 5 to 95°C. Furthermore, in the surface-modified metal-containing silica particle production step (3), the time during which the metal nanoparticles are adsorbed is preferably 0 to 120 hours, more preferably 0 to 72 hours.

[0136] By carrying out the surface-modified metal-containing silica particle producing step (3), a colloidal solution of metal-containing silica particles in which PEG-modified metal nanoparticles are adsorbed on the surfaces of the metal-containing silica particles is obtained.

[0137] In the method for producing surface-modified metal-containing silica particles of the present invention, the colloidal solution of surface-modified metal-containing silica particles obtained by the polyethylene glycol chain introduction step is used, and as necessary, purification, drying, dialysis, concentration, dilution, dispersion treatment, filtration, etc. are carried out to obtain surface-modified metal-containing silica particles in a state appropriate for the intended use.

[0138] The method for producing surface-modified metal-containing silica particles of the present invention does not use a template. By not using a template, precise size adjustment is possible and the production process can be simplified. Furthermore, by not using a template, it is possible to produce silica particles with polyethylene glycol chains present on the surface, which can achieve a high CT value.

[0139] The uses of the surface-modified metal-containing silica particles of the present invention and the surface-modified metal-containing silica particles obtainable by the method for producing the surface-modified metal-containing silica particles of the present invention, that is, "biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with a biocompatible molecule having a thiol group, an amino group, and / or a carboxyl group, and a plurality of which are contained inside the particles, and a polyethylene glycol chain is present on the particle surface" include, for example, angiographic agents, urographic agents, lymph node imaging agents, markers for radiotherapy, catalysts, biomarkers, dyes, carriers, drug delivery particles, photoacoustic imaging materials, spectroscopic tags, photonic applications, and the like.

[0140] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Examples

[0141] (Example 1) [Preparation of GSH-Modified Au Nanoparticles] To 811 mL of distilled water, 40 mL of a 2.5×10 -2 M glutathione (GSH) aqueous solution and 100 mL of a 0.01 M HAuCl4 aqueous solution were added and stirred for 5 minutes. 35 mL of a 0.07 M tetrakis(hydroxymethyl)phosphonium chloride aqueous solution and 14 mL of a 1.0 M NaOH aqueous solution were added and stirred at 35 °C for 24 hours to prepare a GSH-modified Au (denoted as Au GSH ) nanoparticle colloidal solution. Au GSH The nanoparticle colloidal solution was concentrated by an evaporator and dialyzed for 12 hours using a dialysis cellulose tube. The dialysis solution was dried by an evaporator and further vacuum-dried to obtain a powder of Au GSH nanoparticles. The powder of Au GSH nanoparticles was added to water so that the concentration became 2.02 mg / mL, and dispersed using an ultrasonic cleaner to prepare an Au GSH nanoparticle colloidal solution.

[0142] <Au GSH / Preparation of SiO2 nanoparticles> The above Au GSH 3.225 mL of the nanoparticle colloid solution was added to a mixture of 1.508 mL of water and 2.508 mL of ethanol. Next, 17.688 mL of tetraethoxysilane solution diluted 100 times with ethanol was added, and the mixture was stirred for 15 minutes at 35°C. 0.0250 mL of 1.0 M NaOH aqueous solution was added as a basic catalyst, and the mixture was stirred for 5 hours. 25 mL of the resulting reaction mixture was centrifuged at 24,000 rpm for 30 minutes each time, and the solid was redispersed in 9.958 mL of distilled water to obtain Au. GSH SiO2(Au GSH A colloidal solution of nanoparticles (denoted as SiO2 / SiO2) was prepared.

[0143] <Au GSH / SiO2 NH2 Nanoparticle production> Au GSH 0.042 mL of (3-aminopropyl)trimethoxysilane (APTMS) was added as an amino group modifier to the / SiO2 nanoparticle colloidal solution. After stirring for 1 hour at 35°C, the resulting reaction solution was centrifuged for solid-liquid separation, and the solid was redispersed in 5 mL of distilled water to obtain the amino group-modified Au nanoparticles. GSH / SiO2(Au GSH / SiO2 NH2 A nanoparticle colloidal solution (hereinafter referred to as "a colloidal solution") was prepared.

[0144] <Au GSH / SiO2 NH2 / Preparation of PEG nanoparticles> The above Au GSH / SiO2 NH2 5 mL of the nanoparticle colloid solution was added with 5 mL of an aqueous solution of α-mercaptoethyl-ω-methoxypolyoxyethylene (10 g / L, weight-average molecular weight Mw = 5000) as a PEG modifier. The mixture was stirred for 1 hour at 35°C, and then centrifuged three times at 24,000 rpm for 30 minutes to separate the solid and liquid. The solid was then redispersed in 5 mL of distilled water to obtain the PEG-modified Au nanoparticles. GSH / SiO2 NH2 (Au GSH / SiO2NH2 A nanoparticle colloidal solution (denoted as / PEG) was prepared.

[0145] <Measurement of the particle size of Au nanoparticles> Au GSH / SiO2 NH2 The particle size of Au in the / PEG nanoparticles was measured by measuring the minor axis of 100 randomly selected Au particles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH The minor axis of 100 randomly selected Au particles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) was measured, and the measured values were averaged to measure the particle size. GSH The minor axis of 100 randomly selected Au particles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) was measured, and the measured values were averaged to measure the particle size.

[0146] <Measurement of the particle size of Au-containing silica particles> Au GSH The particle size of the Au / SiO2 nanoparticles was measured by measuring the minor axis of 100 randomly selected Au / SiO2 nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH The minor axis of 100 randomly selected Au / SiO2 nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) was measured, and the measured values were averaged to measure the particle size. Also, the particle size of the Au / SiO2 nanoparticles was measured by measuring the minor axis of 100 randomly selected Au / SiO2 nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH / SiO2 NH2 [[ID=3l]]The particle size of the Au / SiO2 nanoparticles was measured by measuring the minor axis of 100 randomly selected Au / SiO2 nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH / SiO2 NH2 The minor axis of 100 randomly selected Au / SiO2 nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) was measured, and the measured values were averaged to measure the particle size. Also, the particle size of the Au / SiO2 / PEG nanoparticles was measured by measuring the minor axis of 100 randomly selected Au / SiO2 / PEG nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH / SiO2 NH2 The particle size of the Au / SiO2 / PEG nanoparticles was measured by measuring the minor axis of 100 randomly selected Au / SiO2 / PEG nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) and averaging the obtained values. GSH / SiO2 NH2 The minor axis of 100 randomly selected Au / SiO2 / PEG nanoparticles in the TEM image obtained under the condition of an acceleration voltage of 200 kV using transmission electron microscopy (TEM) (JEM-2100, manufactured by JEOL Ltd.) was measured, and the measured values were averaged to measure the particle size.

[0147] <BSA adsorption test> Au GSH / SiO2 nanoparticles or Au GSH / SiO2 NH2 The measurement sample was prepared by adding bovine serum albumin (BSA) as a protein to the / PEG nanoparticle colloidal solution. 1 mL of 1 g / L BSA / PBS was added to 1 mL of the above dispersion, followed by pipetting and ultrasonic dispersion, and then allowed to stand on ice for 1 hour. After centrifugation, the sample was vacuum dried, and the amount of BSA adsorption was measured using TG-DTA.

[0148] <Animaging test> Au GSH The / SiO2 nanoparticle colloidal solution was concentrated, and in vitro CT imaging was evaluated using an X-ray CT imaging system.

[0149] <Result> Au GSH Nanoparticles: As shown in Figure 1, spherical particles (average particle size: 1.7 nm) were generated. As shown in Figure 2, Au GSH In the FT-IR spectrum of the nanoparticles, -1 The peaks derived from the SH groups of GSH were not observed in the Au nanoparticles. This is thought to be due to the disappearance of the peaks due to the covalent bonding of the SH groups of GSH to the Au nanoparticles. This indicates that the Au nanoparticles were modified with GSH. Au GSH / SiO2 nanoparticles: Au as shown in Figure 3 GSH Spherical particles containing nanoparticles (average particle size: 38.3 nm) were produced. The particles had no isoelectric point and were negatively charged. Figure 4 shows the Au GSH FT-IR spectrum of the SiO2 nanoparticles. Au GSH / SiO2 NH2 Nanoparticles: Au as shown in Figure 5 GSH Spherical particles containing nanoparticles (average particle size: 36.4 nm) were produced. The particles had an isoelectric point of 7.5 and were positively charged in the acidic to neutral range. This is thought to be due to the cationization of the SiO2 surface by the addition of APTMS. Au GSH / SiO2 NH2 / PEG nanoparticles: As shown in Fig. 6, spherical particles containing Au GSH nanoparticles (average particle size: 40.3 nm) were produced. Au GSH / SiO2 NH2 When compared, the absolute value of the ζ-potential decreased by about 13 mV. This is considered to be because the addition of PEG reduced the charge density on the particle surface. BSA adsorption test: The BSA adsorption test of Au GSH / SiO2 nanoparticles was 6.67 μg, and the BSA adsorption test of Au GSH / SiO2 NH2 / PEG nanoparticles was 5.37 μg. The amount of BSA adsorbed decreased due to PEG modification. From this, an improvement in the biocompatibility of the prepared particles was shown. Imaging contrast test: In vitro, X-ray CT imaging contrast of Au GSH / SiO2 nanoparticles was possible. From this, the prepared particles can be used as an X-ray CT imaging contrast agent.

[0150] (Example 2) <Preparation of GSH-modified Au nanoparticles> To 811 mL of distilled water, 40 mL of a 2.5×10 -2 M glutathione (GSH) aqueous solution and 100 mL of a 0.01 M HAuCl4 aqueous solution were added and stirred for 5 minutes. 35 mL of a 0.07 M tetrakis(hydroxymethyl)phosphonium chloride aqueous solution and 14 mL of a 1.0 M NaOH aqueous solution were added and stirred at 35 °C for 24 hours to prepare a GSH-modified Au (denoted as Au GSH ) nanoparticle colloidal solution. Au GSH nanoparticle colloidal solution was concentrated by an evaporator and dialyzed for 12 hours using a dialysis cellulose tube. The dialysis solution was dried by an evaporator and further vacuum dried to obtain a powder of Au GSH nanoparticles. The powder of Au GSH nanoparticles was added to water to a concentration of 2.02 mg / mL and dispersed using an ultrasonic cleaner to prepare an Au GSH nanoparticle colloidal solution.

[0151] <Au GSH / Preparation of SiO2 nanoparticles> The above Au GSH 3.225 mL of the nanoparticle colloid solution was added to a mixture of 1.508 mL of water and 2.508 mL of ethanol. Then, 17.688 mL of tetraethoxysilane solution diluted 100 times with ethanol was added, and the mixture was stirred for 15 minutes at 35°C. 0.0250 mL of 1.0 M NaOH aqueous solution was added as a basic catalyst, and the mixture was stirred for 5 hours. The resulting 25 mL of reaction solution was centrifuged for solid-liquid separation, and the solid was redispersed in 15.625 mL of distilled water to obtain Au. GSH SiO2(Au GSH A colloidal solution of nanoparticles (denoted as SiO2 / SiO2) was prepared.

[0152] <Au GSH / SiO2 PDADMAC Nanoparticle production> Au GSH The cationic polymer-modified Au was obtained by adding 9.375 mL of a 6.4 g / L aqueous solution of polydiallyldimethylammonium chloride (PDADMAC) to the SiO2 nanoparticle colloidal solution, stirring for 1 hour at 35°C, and then centrifuging to separate the solids. The solids were then redispersed in a mixture of 7.2 mL of ethanol and 0.3 mL of distilled water. GSH / SiO2(Au GSH / SiO2 PDADMAC A nanoparticle colloidal solution (hereinafter referred to as "a colloidal solution") was prepared.

[0153] <Au GSH / SiO2 PDADMAC / Au PEG Nanoparticle production> Au GSH / SiO2 PDADMAC 1.0 x 10 nanoparticle colloidal solution -312.5 mL of the MAu nanoparticle dispersion was added, followed by 5 mL of an α-Mercaptoethyl-ω-methoxy, polyoxyethylene aqueous solution at 8.75 mg / mL, and the mixture was stirred at 35 °C for 24 hours. Further, centrifugation was performed for solid-liquid separation, and the solid was redispersed in 5 mL of distilled water to obtain Au nanoparticles modified with GSH inside and Au nanoparticles modified with PEG on the surface, GSH / SiO2 PDADMAC / Au PEG nanoparticle colloidal solution.

[0154] <Measurement of the particle size of Au nanoparticles> Au GSH / SiO2 PDADMAC ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​PEG The nanoparticles were analyzed by dynamic light scattering (Zetasizer nano ZS90, Malvern). <Ultraviolet-visible spectroscopy (US-vis) analysis> Au GSH / SiO2 PDADMAC / Au PEG The nanoparticles were analyzed by UV-visible spectroscopy (UV3101PC, Shimadzu Corporation).

[0157] <Result> Au GSH / SiO2 PDADMAC / Au PEG Nanoparticles: As shown in Figure 7, spherical particles (particle size: 41.9 nm) were generated with GSH-modified Au nanoparticles inside and PEG-modified Au nanoparticles on the surface. TEM observation confirmed the black contrast between the inside and outside of the particles. Au synthesized in Example 2 GSH / SiO2 PDADMAC / Au PEG When the nanoparticles were subjected to dynamic light scattering analysis, a single peak was observed, as shown in Figure 8. This indicates that the Au GSH / SiO2 PDADMAC / Au PEG This suggests that the nanoparticles do not contain aggregates. GSH / SiO2 PDADMAC / Au PEG When the nanoparticles were subjected to ultraviolet-visible spectroscopy (UV-vis), no peak due to Au was observed around 520 nm, as shown in Figure 9. This suggests that no aggregation of Au particles occurred.

Claims

1. Surface-modified metal-containing silica particles characterized in that the particles contain multiple biocompatible molecule-modified metal nanoparticles inside, in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group and / or a carboxyl group, and polyethylene glycol chains are present on the particle surface.

2. 2. The surface-modified metal-containing silica particles according to claim 1, wherein the particle surface is chemically modified with a surface modifier having a polyethylene glycol chain.

3. The surface-modified metal-containing silica particles described in claim 1 are characterized in that they are silica particles in which PEG-modified metal nanoparticles, in which Au nanoparticles or Pt nanoparticles are surface-modified with a surface modifier having a polyethylene glycol chain, are electrostatically adsorbed to the particle surface.

4. The surface-modified metal-containing silica particles according to any one of claims 1 to 3, characterized in that the biocompatible molecule is a compound selected from the group consisting of glutathione, cysteine, cysteamine, polyethylene glycol having an amino group at one end of the polyethylene glycol chain and a thiol group at the other end, and polyethylene glycol having a carboxyl group at one end of the polyethylene glycol chain and a thiol group at the other end.

5. 4. The surface-modified metal-containing silica particles according to claim 1, wherein the particle diameter of the biocompatible molecule-modified metal nanoparticles is 15 nm or less.

6. 2. The surface-modified metal-containing silica particles according to claim 1, wherein the particle diameter is greater than 15 nm and not greater than 1 μm.

7. A contrast agent comprising the surface-modified metal-containing silica particles according to any one of claims 1 to 3.

8. a reaction raw material liquid preparation step of adding tetraalkoxysilane or a derivative thereof to a colloidal solution containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material liquid; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; 2. A method for producing metal-containing silica particles, comprising:

9. a reaction raw material liquid preparation step of adding tetraalkoxysilane or a derivative thereof to a colloidal solution containing biocompatible molecule-modified metal nanoparticles in which Au nanoparticles or Pt nanoparticles are surface-modified with biocompatible molecules having a thiol group and an amino group or a carboxyl group, thereby obtaining a reaction raw material liquid; a metal-containing silica particle production step in which an alkali catalyst is added to the reaction raw material solution to hydrolyze and polycondense tetraalkoxysilane or a derivative thereof, thereby obtaining a colloidal solution of metal-containing silica particles containing a plurality of the biocompatible molecule-modified metal nanoparticles inside the particles; a biocompatible molecular chain introduction step of introducing biocompatible molecular chains into the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; 1. A method for producing surface-modified metal-containing silica particles, comprising:

10. The method for producing surface-modified metal-containing silica particles according to claim 9, characterized in that the biocompatible molecular chain introduction process is a polyethylene glycol chain introduction process for introducing a polyethylene glycol chain into the metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles.

11. The polyethylene glycol chain introduction step comprises at least an amino group-modified silica particle producing step of adding an amino group modifying agent to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the amino group-modified metal-containing silica particles; a surface-modified metal-containing silica particle producing step of adding a surface modifier having a polyethylene glycol chain to the colloidal solution of the amino group-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles; 11. The method for producing surface-modified metal-containing silica particles according to claim 10, characterized in that the step of:

12. The polyethylene glycol chain introduction step comprises at least a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the cationic polymer-modified metal-containing silica particles; a surface-modified metal-containing silica particle producing step of adding Au nanoparticles or Pt nanoparticles as metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles, and then adding a surface modifier having a polyethylene glycol chain to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; 11. The method for producing surface-modified metal-containing silica particles according to claim 10, characterized in that the step of:

13. The polyethylene glycol chain introduction step comprises at least a cationic polymer-modified metal-containing silica particle producing step of adding a cationic polymer to the colloidal solution of the metal-containing silica particles to obtain a colloidal solution of the cationic polymer-modified metal-containing silica particles; a PEG-modified metal nanoparticle production step of adding a surface modifier having a polyethylene glycol chain to a solution containing Au nanoparticles or Pt nanoparticles as metal nanoparticles to produce PEG-modified metal nanoparticles; a surface-modified metal-containing silica particle producing step of adding the PEG-modified metal nanoparticles to the colloidal solution of the cationic polymer-modified metal-containing silica particles to obtain a colloidal solution of surface-modified metal-containing silica particles in which the PEG-modified metal nanoparticles are electrostatically adsorbed onto the surfaces of the cationic polymer-modified metal-containing silica particles; 11. The method for producing surface-modified metal-containing silica particles according to claim 10, characterized in that the step of:

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