A method for preparing stable gold nanocapsules with adjustable surface properties

Abstract

The invention provides a method for preparing a stable gold nanocapsule with adjustable surface properties, belonging to the field of interface modification. The method first prepares gold nanoparticles stabilized by sodium citrate, replaces the amino ligand of thiol polyethylene glycol, obtains gold nanoparticles modified by polyethylene glycol with amino groups at the end, then adds N-hydroxysuccinimide acrylate to the solution, reacts with the amino groups on the surface of the gold nanoparticles, obtains gold nanoparticles modified by polyethylene glycol with double bonds at the end, finally adds a reactive monomer, a cross-linking agent and an initiator to the solution, performs in-situ free radical polymerization, and prepares gold nanocapsules with a core-shell structure. The nanocapsules have higher stability than gold nanoparticles modified by polyethylene glycol.

Description

Technical Field

[0001] The invention belongs to the field of interface modification, and in particular relates to a method for preparing a stable gold nanocapsule with adjustable surface properties. Background Art

[0002] Gold nanoparticles have excellent photophysical properties and are widely used in the biomedical field, such as biological probes, biomedical imaging, drug delivery carriers, photothermal and photoacoustic therapy, etc. However, gold nanoparticles with high surface energy are thermodynamically unstable and easily aggregate and precipitate, which leads to the disappearance of their surface plasmon resonance characteristic absorption peak. In order to improve the stability of gold nanoparticles, it is usually necessary to modify the surface of gold nanoparticles. Currently, the commonly used surface modification methods include traditional synthetic ligand modification, organic / inorganic polymer modification, metal shell modification and biomacromolecule modification. However, in the biomedical field, how to controllably modify the surface of gold nanoparticles to improve their stability in complex physiological environments still faces great challenges. Therefore, the development of a method for preparing gold nanoparticles modified with a stable cross-linked polymer shell has a good application prospect in the biomedical field. A stable gold nanocapsule is now prepared by in situ free radical polymerization. This method can encapsulate gold nanoparticles of different sizes (3.7 nm, 6 nm, 9 nm, 13 nm, 22.5 nm, 30 nm, 40 nm, etc.) and has excellent stability, which is conducive to further application in the biomedical field.

[0003] It has been reported that the surface of biomacromolecules can be modified by in situ free radical polymerization (YAN M, DU J, GU Z, et al. A novel intracellular protein delivery platform based on single-protein nanocapsules [J]. Nat Nanotechnol, 2010, 5(1): 48-53.). The specific steps are as follows: (1) mixing the biomacromolecule with N-hydroxysuccinimide acrylate solution to obtain a protein with double bonds modified on the surface; (2) adding monomers, crosslinking agents, catalysts, and initiators to the solution of the biomacromolecules with double bonds, and performing in situ free radical polymerization on the surface of the biomacromolecule to obtain biomacromolecule nanocapsules. However, this modification method has not yet been applied to the field of inorganic nanoparticles. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a stable gold nanocapsule with adjustable surface properties. Gold nanoparticles of different sizes (3.7 nm-40 nm) can be successfully encapsulated into gold nanocapsules by surface modification.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a stable gold nanocapsule with adjustable surface properties, and the steps are as follows:

[0007] Step 1: preparing gold nanoparticle solution;

[0008] Step 2: Mixing the gold nanoparticle solution of step 1 and the thiol polyethylene glycol amino solution to obtain a thiol polyethylene glycol amino-modified gold nanoparticle solution;

[0009] Step 3: adding N-hydroxysuccinimide acrylate solution to the thiol-polyethylene glycol amino-modified gold nanoparticle solution in step 2 to react and obtain N-hydroxysuccinimide acrylate-modified gold nanoparticle solution;

[0010] Step 4: Add an acryloyl polymer monomer containing a double bond, a crosslinking agent and a buffer solution into a reaction container to obtain a mixed solution, then add the N-hydroxysuccinimide acrylate-modified gold nanoparticle solution of step 3 into the above mixed solution, then add tetramethylethylenediamine solution and stir evenly, and finally add ammonium persulfate solution to react to obtain gold nanocapsules.

[0011] Preferably, the particle size of the gold nanoparticles in step 1 is 3.7 nm-40 nm.

[0012] Preferably, the volume ratio of the gold nanoparticle solution, the mercapto polyethylene glycol amino solution and the N-hydroxysuccinimide acrylate solution is 1:(0.06-0.2):(0.051-0.185).

[0013] Preferably, the reaction temperature in step 2 is room temperature, and the reaction time is 12-24 hours.

[0014] Preferably, the reaction temperature in step 3 is room temperature, and the reaction time is more than 4 hours.

[0015] Preferably, the double bond-containing acrylic polymer monomer described in step 4 is one or more of acrylamide, N-(3-aminopropyl)methacrylamide, 2-methacryloyloxyethyl phosphorylcholine, 2-acrylamide-2-methylpropanesulfonic acid or acrylate-polyethylene glycol-succinimide carboxymethyl ester.

[0016] Preferably, the cross-linking agent in step 4 is N,N'-methylenebisacrylamide, glycerol 1,3-dimethacrylate, dimethyl acrylate or polyethylene glycol diacrylate.

[0017] Preferably, the volume ratio of the double-bond-containing acrylic polymer monomer, the crosslinking agent, the N-hydroxysuccinimide acrylate-modified gold nanoparticle solution, the tetramethylethylenediamine solution and the ammonium persulfate solution in step 4 is 35.5:15.4:500:5.9:22.8.

[0018] Preferably, the concentration of the double bond-containing acryloyl polymer monomer in step 4 is 200 mg / mL, the concentration of the N-hydroxysuccinimide acrylate-modified gold nanoparticle solution is 1 mg / mL, the concentration of the tetramethylethylenediamine solution is 775 mg / mL, and the concentration of the ammonium persulfate solution is 100 mg / mL.

[0019] Preferably, the reaction temperature in step 4 is room temperature, and the reaction time is more than 2 hours.

[0020] Beneficial effects of the present invention

[0021] The present invention provides a method for preparing a stable gold nanocapsule with adjustable surface properties. The nanocapsule is a nanostructure with a cross-linked structure, which uses gold nanoparticles as a core and a polymer as a shell. The method uses an in-situ free radical polymerization method to modify the surface of gold nanoparticles, introduces double bond polymerization sites on the surface of gold nanoparticles and initiates in-situ free radical polymerization. Compared with the existing gold nanoparticle modification method, the present invention uses an in-situ free radical polymerization method to modify double bonds on the surface of gold nanoparticles as polymerization sites, adds monomers and crosslinking agents, and polymerizes and modifies a layer of cross-linked polymer shell on the surface of gold nanoparticles under the TEMED and APS initiation system, which effectively improves its stability. In addition, the flexibility of monomer selection of the gold nanocapsule of the present invention provides the possibility of precise regulation of its surface properties. In particular, acrylate-polyethylene glycol-succinimide carboxymethyl ester is used as a monomer to introduce specific reaction sites on the surface of the gold nanocapsule. These sites can effectively couple biomolecules, thereby giving the gold nanocapsule a long circulation characteristic. This modification strategy significantly enhances the application potential of gold nanocapsules in the biomedical field, making it an ideal drug delivery and bioimaging carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Transmission electron microscopy images of gold nanoparticles and gold nanocapsules prepared in Examples 1-5 of the present invention;

[0023] Figure 2 This is a graph showing the changes in the hydrodynamic particle sizes of Au NPs, Au-PEG, Au-PEG-NAS and n(Au) during the preparation of the gold nanocapsules prepared in Example 4 of the present invention;

[0024] Figure 3is the infrared spectra of Au-PEG, Au-PEG-NAS and n(Au) in Example 4 of the present invention;

[0025] Figure 4 The stability test curve of the gold nanocapsules prepared in Example 4 of the present invention under different conditions;

[0026] Figure 5 Surface potential maps of 13 nm gold nanocapsules encapsulated with different monomers were prepared to change the monomer types;

[0027] Figure 6 The graph shows the specific adsorption of TSP-1 by phosphate buffer solution PBS, LSKL, n(Au) and n(Au)-LSKL respectively;

[0028] Figure 7 This is a graph showing the measurement of gold content in the blood of mice at different times when n(Au) and n(Au)-LSKL were added. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a stable gold nanocapsule with adjustable surface properties, and the steps are as follows:

[0030] Step 1: prepare a gold nanoparticle (Au NPs) solution; the particle size of the gold nanoparticles is preferably 3.7 nm-40 nm, more preferably 3.7 nm, 6 nm, 9 nm, 13 nm, 22.8 nm, 25.5 nm, 30 nm, 40 nm. There is no special limitation on the preparation of the gold nanoparticle solution, and it can be prepared by methods well known in the art.

[0031] Step 2: Mix the gold nanoparticle solution of step 1 and the thiol polyethylene glycol amino solution for reaction, the reaction temperature is preferably room temperature, the reaction time is preferably 12-24 hours, and a thiol polyethylene glycol amino-modified gold nanoparticle solution (Au-PEG) is obtained; the volume ratio of the gold nanoparticle solution to the thiol polyethylene glycol amino solution is preferably 1: (0.06-0.2), wherein the concentration of the gold nanoparticle solution is preferably 1 mg / mL, and the concentration of the thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) is preferably 50 mg / mL;

[0032] Step 3: Adding N-hydroxysuccinimide acrylate solution to the thiol polyethylene glycol amino modified gold nanoparticle solution of step 2 for reaction, wherein the reaction temperature is preferably room temperature, and the reaction time is preferably more than 4 hours, more preferably 4 hours, to obtain N-hydroxysuccinimide acrylate modified gold nanoparticle solution (Au-PEG-NAS); the volume ratio of the thiol polyethylene glycol amino solution to the N-hydroxysuccinimide acrylate solution is preferably (0.06-0.2): (0.051-0.185), wherein the concentration of the N-hydroxysuccinimide acrylate solution (NAS) is preferably 10 mg / mL;

[0033] Step 4: Add an acrylic polymer monomer containing a double bond, a cross-linking agent and a buffer solution into a reaction container to obtain a mixed solution, then add the N-hydroxysuccinimide acrylate modified gold nanoparticle solution of step 3 into the above mixed solution, then add tetramethylethylenediamine solution and stir evenly, and finally add ammonium persulfate solution to react. The reaction temperature is preferably room temperature, and the reaction time is preferably more than 2 hours, more preferably 2 hours, to obtain gold nanocapsules (n(Au)).

[0034] The double bond-containing acrylic polymer monomer is preferably one or more of acrylamide (AAM), N-(3-aminopropyl) methacrylamide (APM), 2-methacryloyloxyethyl phosphorylcholine (MPC), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or acrylate-polyethylene glycol-succinimidyl carboxymethyl ester (SCM-PEG-NHS), and more preferably AAM, MPC, a mixture of AAM and APM (wherein the molar ratio of AAM:APM is 10:1), a mixture of AAM and AMPS (wherein the molar ratio of AAM:AMPS is 10:1), a mixture of MPC and APM (wherein the molar ratio of MPC:APM is 10:1), a mixture of MPC and AMPS (wherein the molar ratio of MPC:AMPS is 10:1), a mixture of MPC and SCM-PEG-NHS (wherein the molar ratio of MPC: The molar ratio of SCM-PEG-NHS is 10:1), and the cross-linking agent is preferably N,N'-methylenebisacrylamide (BIS), glycerol 1,3-diisomethacrylate, dimethyl acrylate or polyethylene glycol diacrylate.

[0035] According to the present invention, the volume ratio of the acrylic polymer monomer containing double bonds, the crosslinking agent, the gold nanoparticle solution modified by N-hydroxysuccinimide acrylate, the tetramethylethylenediamine solution and the ammonium persulfate solution is preferably 35.5:15.4:500:5.9:22.8. The concentration of the acrylic polymer monomer containing double bonds is preferably 200 mg / mL, the concentration of the crosslinking agent is preferably 100 mg / mL, the concentration of the gold nanoparticle solution modified by N-hydroxysuccinimide acrylate is preferably 1 mg / mL, the concentration of the tetramethylethylenediamine solution is preferably 775 mg / mL, and the concentration of the ammonium persulfate solution is preferably 100 mg / mL.

[0036] The present invention is further described in detail below with reference to specific examples, and the raw materials involved in the examples are all commercially available. Example 1

[0037] (1) Preparation of gold nanoparticles (Au NPs)

[0038] 3.7 nm Au NPs: Take a 20 mL glass bottle, add 0.2 mL of 25 mM chloroauric acid solution, 64.52 μL of 20 mg / mL sodium citrate solution and 19.8 mL of deionized water, then add 0.6 mL of 3.78 mg / mL ice-cold sodium borohydride solution while stirring vigorously, react for 2 h and set aside.

[0039] (2) Amino-modified gold nanoparticles with thiol-polyethylene glycol (Au-PEG)

[0040] Take 1 mL of 1 mg / mL Au NPs solution, add 200 μL of 50 mg / mL thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) to the solution, and react at room temperature for 12 h.

[0041] (3) N-hydroxysuccinimide acrylate modified gold nanoparticles (Au-PEG-NAS)

[0042] Add 185 μL of 10 mg / mL N-hydroxysuccinimide acrylate solution (NAS) to the Au-PEG solution and react at room temperature for 4 h.

[0043] (4) Gold nanocapsules (n(Au))

[0044] Add 35.5 μL of 200 mg / mL acrylamide solution as monomer, 15.4 μL of 100 mg / mL N,N'-methylenebisacrylamide solution as crosslinker, 100 μL of 0.1 mol / L phosphate buffer solution, and 320 μL of deionized water to a 1.5 mL centrifuge tube and stir evenly. Add 500 μL of 1 mg / mL Au-PEG-NAS solution and stir evenly. Add 5.9 μL of 775 mg / mL tetramethylethylenediamine solution (TEMED) and stir evenly. Finally, add 22.8 μL of 100 mg / mL ammonium persulfate solution (APS), stir evenly, and react at room temperature for 2 h to obtain a 0.5 mg / mL n(Au) solution. Example 2

[0045] (1) Preparation of gold nanoparticles (Au NPs)

[0046] 6 nm Au NPs: Add 0.5 mL of 50 mM chloroauric acid solution, 42.5 μL of 0.1wt% silver nitrate solution, and 2.5 mL of 10 mg / mL sodium citrate solution to a 5 mL centrifuge tube, mix well, and incubate at room temperature for 16 minutes. Add the above solution to a round-bottom flask containing 47.5 mL of deionized water and keep boiling for 30 minutes.

[0047] (2) Amino-modified gold nanoparticles with thiol-polyethylene glycol (Au-PEG)

[0048] Take 1 mL of 1 mg / mL Au NPs solution, add 152 μL of 50 mg / mL thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) to the solution, and react at room temperature for 12 h.

[0049] (3) N-hydroxysuccinimide acrylate modified gold nanoparticles (Au-PEG-NAS)

[0050] Add 129 μL of 10 mg / mL N-hydroxysuccinimide acrylate solution (NAS) to the Au-PEG solution and react at room temperature for 4 h.

[0051] (4) Gold nanocapsules (n(Au))

[0052] Add 35.5 μL of 200 mg / mL acrylamide solution as monomer, 15.4 μL of 100 mg / mL N,N'-methylenebisacrylamide solution as crosslinker, 100 μL of 0.1 mol / L phosphate buffer solution, and 320 μL of deionized water to a 1.5 mL centrifuge tube and stir evenly. Add 500 μL of 1 mg / mL Au-PEG-NAS solution and stir evenly. Add 5.9 μL of 775 mg / mL tetramethylethylenediamine solution (TEMED) and stir evenly. Finally, add 22.8 μL of 100 mg / mL ammonium persulfate solution (APS), stir evenly, and react at room temperature for 2 h to obtain a 0.5 mg / mL n(Au) solution. Example 3

[0053] (1) Preparation of gold nanoparticles (Au NPs)

[0054] 9 nm Au NPs: Add 0.5 mL of 50 mM chloroauric acid solution, 42.5 μL of 0.1wt% silver nitrate solution, 1.5 mL of 10 mg / mL sodium citrate solution, and 1 mL of deionized water to a 5 mL centrifuge tube, mix well, and incubate at room temperature for 8 minutes. Add the above solution to a round-bottom flask containing 47.5 mL of deionized water and keep boiling for 30 minutes.

[0055] (2) Amino-modified gold nanoparticles with thiol-polyethylene glycol (Au-PEG)

[0056] Take 1 mL of 1 mg / mL Au NPs solution, add 112 μL of 50 mg / mL thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) to the solution, and react at room temperature for 12 h.

[0057] (3) N-hydroxysuccinimide acrylate modified gold nanoparticles (Au-PEG-NAS)

[0058] Add 95 μL of 10 mg / mL N-hydroxysuccinimide acrylate solution (NAS) to the Au-PEG solution and react at room temperature for 4 h.

[0059] (4) Gold nanocapsules (n(Au))

[0060] Add 35.5 μL of 200 mg / mL acrylamide solution as monomer, 15.4 μL of 100 mg / mL N,N'-methylenebisacrylamide solution as crosslinker, 100 μL of 0.1 mol / L phosphate buffer solution, and 320 μL of deionized water to a 1.5 mL centrifuge tube and stir evenly. Add 500 μL of 1 mg / mL Au-PEG-NAS solution and stir evenly. Add 5.9 μL of 775 mg / mL tetramethylethylenediamine solution (TEMED) and stir evenly. Finally, add 22.8 μL of 100 mg / mL ammonium persulfate solution (APS), stir evenly, and react at room temperature for 2 h to obtain a 0.5 mg / mL n(Au) solution. Example 4

[0061] (1) Preparation of gold nanoparticles (Au NPs)

[0062] 13 nm Au NPs: Take a round-bottom flask, add 96 mL of deionized water, 2 mL of 15 mM chloroauric acid solution and heat to a slight boil, add 2 mL of 20 mg / mL sodium citrate solution, heat to reflux, keep boiling for 15 min, and then cool for use.

[0063] (2) Amino-modified gold nanoparticles with thiol-polyethylene glycol (Au-PEG)

[0064] Take 1 mL of 1 mg / mL Au NPs solution, add 60 μL of 50 mg / mL thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) to the solution, and react at room temperature for 12 h.

[0065] (3) N-hydroxysuccinimide acrylate modified gold nanoparticles (Au-PEG-NAS)

[0066] Add 51 μL of 10 mg / mL N-hydroxysuccinimide acrylate solution (NAS) to the Au-PEG solution and react at room temperature for 4 h.

[0067] (4) Gold nanocapsules (n(Au))

[0068] Add 35.5 μL of 200 mg / mL acrylamide solution as monomer, 15.4 μL of 100 mg / mL N,N'-methylenebisacrylamide solution as crosslinker, 100 μL of 0.1 mol / L phosphate buffer solution, and 320 μL of deionized water to a 1.5 mL centrifuge tube and stir evenly. Add 500 μL of 1 mg / mL Au-PEG-NAS solution and stir evenly. Add 5.9 μL of 775 mg / mL tetramethylethylenediamine solution (TEMED) and stir evenly. Finally, add 22.8 μL of 100 mg / mL ammonium persulfate solution (APS), stir evenly, and react at room temperature for 2 h to obtain a 0.5 mg / mL n(Au) solution. Example 5

[0069] (1) Preparation of gold nanoparticles (Au NPs)

[0070] 22.8, 25.5, 30, 40 nm Au NPs: Preparation:

[0071] Prepare solution A: 10 mL 12 mM chloroauric acid solution; prepare solution B: add 50 mg solid ascorbic acid and 25 mg solid sodium citrate to 10 mL deionized water and dissolve; take a three-necked flask, add 50 mL of freshly prepared 13 nm Au NPs, add 50 mL deionized water, and slowly add 1.4-8 mL of the same volume of solution A and solution B at a speed of 88 μL / min using a syringe pump while stirring. Heat the above solution and keep it boiling for 30 min.

[0072] (2) Amino-modified gold nanoparticles with thiol-polyethylene glycol (Au-PEG)

[0073] Take 1 mL of 1 mg / mL Au NPs solution, add 32-53 μL of 50 mg / mL thiol polyethylene glycol amino solution (SH-PEG-NH2, Mw=2000 g / mol) to the solution, and react at room temperature for 12 h.

[0074] (3) N-hydroxysuccinimide acrylate modified gold nanoparticles (Au-PEG-NAS)

[0075] Add 43-51 μL of 10 mg / mL N-hydroxysuccinimide acrylate solution (NAS) to the Au-PEG solution and react at room temperature for 4 h.

[0076] (4) Gold nanocapsules (n(Au))

[0077] Add 35.5 μL of 200 mg / mL acrylamide solution as monomer, 15.4 μL of 100 mg / mL N,N'-methylenebisacrylamide solution as crosslinker, 100 μL of 0.1 mol / L phosphate buffer solution, and 320 μL of deionized water to a 1.5 mL centrifuge tube and stir evenly. Add 500 μL of 1 mg / mL Au-PEG-NAS solution and stir evenly. Add 5.9 μL of 775 mg / mL tetramethylethylenediamine solution (TEMED) and stir evenly. Finally, add 22.8 μL of 100 mg / mL ammonium persulfate solution (APS), stir evenly, and react at room temperature for 2 h to obtain a 0.5 mg / mL n(Au) solution.

[0078] Figure 1 The transmission electron micrographs of the gold nanoparticles and gold nanocapsules prepared in Examples 1-5 of the present invention are shown in FIG. Figure 1 A is a transmission electron microscopy image of 3.7-13 nm gold nanoparticles; Figure 1 B is the transmission electron microscopy image of 3.7-13 nm gold nanocapsules. Figure 1 C is the transmission electron microscopy image of 22.8-40 nm gold nanoparticles; Figure 1 D is a transmission electron micrograph of 22.8-40 nm gold nanocapsules. From the white polymer shell in the figure, it can be seen that 3.7-40 nm gold nanoparticles were successfully encapsulated into gold nanocapsules.

[0079] Figure 2 The figure is a diagram showing the changes in the hydrodynamic particle sizes of Au NPs, Au-PEG, Au-PEG-NAS and n (Au) during the preparation of the gold nanocapsules prepared in Example 4 of the present invention. It can be seen from the figure that with the modification from Au NPs to n (Au), the hydrodynamic radius of the nanoparticles increases from about 17 nm to about 32 nm, proving the successful encapsulation of the gold nanocapsules.

[0080] Figure 3 The infrared spectra of Au-PEG, Au-PEG-NAS and n(Au) in Example 4 of the present invention are shown in FIG. From the figure, it can be seen that the characteristic peak of polyacrylamide proves that the surface of the gold nanoparticles is modified with a polymer shell containing a polyacrylamide component.

[0081] Figure 4 The stability test curve of the gold nanocapsules prepared in Example 4 of the present invention under different conditions is shown in FIG. Figure 4A is a comparison of the relative absorbance (A / A0) of the absorption peaks of Au NPs, Au-PEG and n(Au) stored in aqueous solution for 0-30 days. It can be observed from the figure that the relative absorbance of n(Au) decreases the least compared with Au NPs and Au-PEG, indicating that n(Au) has better storage stability. Figure 4 B is a comparison of the relative absorbance (A / A0) of the absorption peaks of Au NPs, Au-PEG and n(Au) stored in phosphate buffer solution (PBS) for 12 h and Au NPs, Au-PEG and n(Au) aqueous solutions frozen in a -20°C refrigerator for 12 h. It can be observed from the figure that the relative absorbance of n(Au) decreases the least compared with Au NPs and Au-PEG, indicating that n(Au) has better salt solution stability; Figure 4 C is a comparison of the relative absorbance (A / A0) of the absorption peaks of Au NPs, Au-PEG and n(Au) after being stored in different pH environments for 12 h. It can be observed from the figure that the relative absorbance of n(Au) decreases the least compared with Au NPs and Au-PEG, indicating that n(Au) has better pH stability. It can be seen that gold nanocapsules have high stability under long-term storage, salt solution, low temperature and different pH environments, proving the effective protection ability of this modification method for gold nanoparticles. Example 6

[0082] The preparation steps and conditions were the same as those in Example 4, except that BIS was used as a cross-linking agent and only the type of monomer was changed to prepare 13 nm gold nanocapsules encapsulated by different monomers.

[0083] Figure 5The surface potential diagrams of 13 nm gold nanocapsules wrapped with different monomers were prepared to change the types of monomers. Neutral AAM was used as the reaction monomer to prepare gold nanocapsules, which were labeled as n(Au) / AAM; AAM was used as the main reaction monomer and positively charged APM was used as the secondary reaction monomer (AAM:APM molar ratio = 10:1) to prepare gold nanocapsules, which were labeled as n(Au) / AAM+APM; AAM was used as the main reaction monomer and negatively charged AMPS was used as the secondary reaction monomer (AAM:AMPS molar ratio = 10:1) to prepare gold nanocapsules, which were labeled as n(Au) / AA M+AMPS; zwitterionic monomer MPC is used as a reaction monomer to prepare gold nanocapsules, which are marked as n(Au) / MPC; MPC is used as the main reaction monomer, and positively charged APM is used as a secondary reaction monomer (MPC:APM molar ratio = 10:1), and gold nanocapsules are prepared, which are marked as n(Au) / MPC+APM; MPC is used as the main reaction monomer, and negatively charged AMPS is used as a secondary reaction monomer (MPC:AMPS molar ratio = 10:1), and gold nanocapsules are prepared, which are marked as n(Au) / MPC-AMPS. It can be seen that the modification method of the present invention can achieve the regulation of the surface potential of gold nanocapsules by changing the type and mixing ratio of the monomers. Example 7

[0084] The preparation steps and conditions were the same as those in Example 4, except that BIS was used as a cross-linking agent, MPC was selected as a primary monomer, and SCM-PEG-NHS was selected as a secondary monomer (MPC: SCM-PEG-NHS molar ratio = 10:1) to prepare gold nanocapsules (n(Au)-NHS) with N-hydroxysuccinimide (NHS) groups on the surface.

[0085] The peptide with amino groups on the surface - thrombospondin inhibitor trifluoroacetate (LSKL-NH2) was added to the n(Au)-NHS solution (LSKL-NH2: n(Au)-NHS molar ratio = 2:1), and the gold nanocapsule-peptide conjugate (n(Au)-LSKL) was obtained after 12 h of reaction.

[0086] Figure 6 The figure shows the specific adsorption of TSP-1 by phosphate buffer solution PBS, LSKL, n(Au) and n(Au)-LSKL, respectively. Phosphate buffer solution (PBS) was used as the blank control group, peptide (LSKL) and gold nanocapsule (n(Au)) were used as the experimental control group, and gold nanocapsule-peptide conjugate (n(Au)-LSKL) was used as the experimental group. It can be seen from the figure that the fluorescence intensity of n(Au)-LSKL is the strongest, indicating that n(Au)-LSKL adsorbs the largest amount of TSP-1, proving the successful coupling of n(Au) and LSKL.

[0087] Figure 7 This is a graph of the gold content in the blood of mice at different times after n(Au) and n(Au)-LSKL were injected into the tail vein of mice using an inductively coupled plasma mass spectrometer (ICP-MS). As can be seen from the figure, n(Au)-LSKL exhibits a half-life of 26.2 h, proving that the coupling of gold nanocapsules and peptides has a long half-life.

Claims

1. A method for preparing stable gold nanocapsules with adjustable surface properties, characterized in that: The steps are as follows: Step 1: preparing gold nanoparticle solution; Step 2: Mixing the gold nanoparticle solution of step 1 and the thiol polyethylene glycol amino solution to obtain a thiol polyethylene glycol amino-modified gold nanoparticle solution; Step 3: adding N-hydroxysuccinimide acrylate solution to the thiol-polyethylene glycol amino-modified gold nanoparticle solution in step 2 to react and obtain N-hydroxysuccinimide acrylate-modified gold nanoparticle solution; Step 4: Adding an acryloyl polymer monomer containing a double bond, a crosslinking agent and a buffer solution into a reaction container to obtain a mixed solution, then adding the N-hydroxysuccinimide acrylate modified gold nanoparticle solution of step 3 into the mixed solution, then adding a tetramethylethylenediamine solution and stirring evenly, and finally adding an ammonium persulfate solution to react to obtain gold nanocapsules; The volume ratio of the gold nanoparticle solution, the mercapto polyethylene glycol amino solution and the N-hydroxysuccinimide acrylate solution is 1:(0.06-0.2):(0.051-0.185).

2. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The particle size of the gold nanoparticles in step 1 is 3.7nm-40nm.

3. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The reaction temperature in step 2 is room temperature, and the reaction time is 12-24 hours.

4. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The reaction temperature in step 3 is room temperature, and the reaction time is more than 4 hours.

5. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The double-bond-containing acryloyl polymer monomer described in step 4 is one or more of acrylamide, N-(3-aminopropyl)methacrylamide, 2-methacryloyloxyethyl phosphorylcholine, 2-acrylamide-2-methylpropanesulfonic acid or acrylate-polyethylene glycol-succinimide carboxymethyl ester.

6. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The cross-linking agent in step 4 is N,N'-methylenebisacrylamide, glycerol 1,3-diisomethacrylate, dimethyl acrylate or polyethylene glycol diacrylate.

7. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The volume ratio of the double-bond-containing acrylic polymer monomer, the crosslinking agent, the N-hydroxysuccinimide acrylate-modified gold nanoparticle solution, the tetramethylethylenediamine solution and the ammonium persulfate solution described in step 4 is 35.5:15.4:500:5.9:22.

8.

8. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The concentration of the double-bond-containing acryloyl polymer monomer described in step 4 is 200 mg / mL, the concentration of the N-hydroxysuccinimide acrylate-modified gold nanoparticle solution is 1 mg / mL, the concentration of the tetramethylethylenediamine solution is 775 mg / mL, and the concentration of the ammonium persulfate solution is 100 mg / mL.

9. The method for preparing a stable gold nanocapsule with adjustable surface properties according to claim 1, characterized in that: The reaction temperature in step 4 is room temperature, and the reaction time is more than 2 hours.

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