A gold nanoparticle and a method for preparing the same

Abstract

This invention provides gold nanoparticles and their preparation method, comprising the following components by mass percentage: chloroauric acid 5-5%, quercetin 1-3%, chitosan 0.5-2%, hexadecyltrimethylammonium bromide 0.1-0.5%, and ultrapure water 92-93%; wherein the degree of deacetylation of chitosan is ≥90%. This invention uses natural quercetin instead of sodium borohydride as a reducing agent, reducing toxic byproducts and conforming to green chemistry principles; by using chitosan (degree of deacetylation ≥90%) as a stabilizer, it imparts positive charge properties to the particles, enhancing cellular uptake efficiency and reducing toxicity.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a gold nanoparticle and its preparation method. Background Technology

[0002] Gold nanoparticles (AuNPs) have wide applications in biomedicine, environmental engineering, and electronic devices due to their unique optical, electrical, and catalytic properties. However, current preparation techniques still face the following key challenges: Traditional chemical reduction methods (such as the Turkevich process) rely on strong reducing agents like sodium borohydride, which easily generate toxic byproducts (such as cyanide) during the reaction, limiting their application in the biomedical field. Furthermore, current technologies struggle to produce spherical gold nanoparticles with uniform and controllable particle size. For example, gold nanoparticle films prepared by self-assembly methods have limited area (only on the square centimeter scale) and are prone to aggregation; while microfluidic technology can improve size uniformity, it suffers from channel adsorption and deposition problems, leading to reduced yield.

[0003] In view of the above, this application is hereby submitted. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a gold nanoparticle, characterized by comprising the following components by mass percentage: chloroauric acid 0.5-1.5%, quercetin 0.1-0.3%, chitosan 0.05-0.2%, hexadecyltrimethylammonium bromide 0.01-0.05%, and ultrapure water 97.2-98.3%; Among them, the degree of deacetylation of chitosan is ≥90%.

[0005] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:3-1:5, the concentration of the chitosan solution is 1-2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 0.5-2 mM.

[0006] Secondly, a method for preparing gold nanoparticles includes the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1-0.5 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1-2% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5-1.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0-8.5, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0007] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0008] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0-8.5 in real time using 0.1 M NaOH.

[0009] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0010] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0011] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0012] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0013] The above-described solution of the present invention has at least the following beneficial effects: This invention uses natural quercetin instead of sodium borohydride as a reducing agent to reduce toxic byproducts, conforming to the principles of green chemistry. Chitosan (degree of deacetylation ≥90%) is used as a stabilizer to impart positive charge properties to the particles, enhancing cellular uptake efficiency and reducing toxicity. Monodisperse spherical gold nanoparticles (16.8±3.27 nm) with a PDI <0.1 are obtained through CTAB morphology-directing agent and pH control (8.0-8.5). Crystalline selective growth is achieved through UV-controlled crystallization technology, with tunable longitudinal plasma absorption peaks (750-850 nm), superior to traditional chemical synthesis methods. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0015] This invention provides gold nanoparticles comprising the following components by mass percentage: chloroauric acid 0.5-1.5%, quercetin 0.1-0.3%, chitosan 0.05-0.2%, hexadecyltrimethylammonium bromide 0.01-0.05%, and ultrapure water 97.2-98.3%; Among them, the degree of deacetylation of chitosan is ≥90%.

[0016] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:3-1:5, the concentration of the chitosan solution is 1-2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 0.5-2 mM.

[0017] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1-0.5 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1-2% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5-1.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0-8.5, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0018] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0019] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0-8.5 in real time using 0.1 M NaOH.

[0020] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0021] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0022] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0023] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0024] Example 1:

[0025] A gold nanoparticle comprises the following components by mass percentage: 0.5% chloroauric acid, 0.1% quercetin, 0.05% chitosan, 0.01% hexadecyltrimethylammonium bromide, and 97.2% ultrapure water; wherein the degree of deacetylation of chitosan is ≥90%.

[0026] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:3, the concentration of the chitosan solution is 1% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 0.5 mM.

[0027] This embodiment also provides a method for preparing gold nanoparticles, including the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer. Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0028] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0 in real time using 0.1 M NaOH.

[0029] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0030] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0031] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0032] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0033] Example 2: This invention provides gold nanoparticles comprising the following components by mass percentage: 1.5% chloroauric acid, 0.3% quercetin, 0.2% chitosan, 0.05% hexadecyltrimethylammonium bromide, and 98.3% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0034] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:5, the concentration of the chitosan solution is 2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 2 mM.

[0035] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.5 mM chloroauric acid solution; dissolve chitosan in a 1% aqueous acetic acid solution to prepare a 2% chitosan solution; dissolve quercetin in ethanol to prepare a 1.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.5, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0036] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0037] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.5 in real time using 0.1 M NaOH.

[0038] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0039] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0040] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0041] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0042] Example 3:

[0043] This invention provides gold nanoparticles comprising the following components by mass percentage: 1% chloroauric acid, 0.2% quercetin, 0.1% chitosan, 0.03% hexadecyltrimethylammonium bromide, and 98% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0044] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:4, the concentration of the chitosan solution is 1.5% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 1 mM.

[0045] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.3 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1.5% chitosan solution; dissolve quercetin in ethanol to prepare a 1 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.1, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0046] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0047] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0-8.5 in real time using 0.1 M NaOH.

[0048] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0049] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0050] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0051] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0052] Example 4: This invention provides gold nanoparticles comprising the following components by mass percentage: 1.4% chloroauric acid, 0.2% quercetin, 0.2% chitosan, 0.05% hexadecyltrimethylammonium bromide, and 98.3% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0053] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:5, the concentration of the chitosan solution is 2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 2 mM.

[0054] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.4 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1.5% chitosan solution; dissolve quercetin in ethanol to prepare a 1 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.2, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0055] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0056] Furthermore, in step 3, the amount of CTAB added is 1.2 mM, and the pH of the reaction system is adjusted to 8.3 in real time using 0.1 M NaOH.

[0057] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0058] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0059] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0060] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0061] Example 5:

[0062] This invention provides gold nanoparticles comprising the following components by mass percentage: 0.5% chloroauric acid, 0.3% quercetin, 0.2% chitosan, 0.05% hexadecyltrimethylammonium bromide, and 98.3% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0063] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:5, the concentration of the chitosan solution is 2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 2 mM.

[0064] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1 mM chloroauric acid solution; dissolve chitosan in a 1% aqueous acetic acid solution to prepare a 1% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0065] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0066] Furthermore, in step 3, the amount of CTAB added is 0.5 mM, and the pH of the reaction system is adjusted to 8.0 in real time using 0.1 M NaOH.

[0067] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0068] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0069] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0070] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0071] Example 6:

[0072] This invention provides gold nanoparticles comprising the following components by mass percentage: 1.3% chloroauric acid, 0.2% quercetin, 0.13% chitosan, 0.03% hexadecyltrimethylammonium bromide, and 97.3% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0073] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:4, the concentration of the chitosan solution is 1% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 0.5 mM.

[0074] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.5 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0-8.5, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0075] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0076] Furthermore, in step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0-8.5 in real time using 0.1 M NaOH.

[0077] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0078] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0079] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0080] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0081] Example 7:

[0082] This invention provides gold nanoparticles comprising the following components by mass percentage: 1% chloroauric acid, 0.1% quercetin, 0.05% chitosan, 0.04% hexadecyltrimethylammonium bromide, and 98.2% ultrapure water; Among them, the degree of deacetylation of chitosan is ≥90%.

[0083] Furthermore, the molar ratio of chloroauric acid to quercetin is 1:3, the concentration of the chitosan solution is 2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 2 mM.

[0084] This invention also provides a method for preparing gold nanoparticles, comprising the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1-0.5 mM chloroauric acid solution; dissolve chitosan in 1% acetic acid aqueous solution to prepare a 1-2% chitosan solution; dissolve quercetin in ethanol to prepare a 1.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.3, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

[0085] Furthermore, it also includes: Step 4: Surface-modify the target peptide (e.g., RGDS) or load the drug (e.g., melphalan), with an encapsulation efficiency >85%.

[0086] Furthermore, in step 3, the amount of CTAB added is 1.3 mM, and the pH of the reaction system is adjusted to 8.1 in real time using 0.1 M NaOH.

[0087] Furthermore, in step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

[0088] Furthermore, the spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

[0089] Furthermore, in step 3, the stirring conditions are 400 rpm for 30 minutes.

[0090] Furthermore, in step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

[0091] This invention utilizes quercetin (a plant-derived flavonoid) instead of traditional sodium borohydride as a reducing agent, combined with chitosan (deacetylation degree ≥90%) as a stabilizer, to construct a green and environmentally friendly synthesis system, eliminating the environmental pollution risks of heavy metal residues and toxic byproducts (such as cyanide) at the source. This process can complete the reaction at room temperature and under static conditions, without requiring harsh conditions such as high temperature / strong acid, making it simple to operate and reducing energy consumption by 40%, making it particularly suitable for continuous industrial production. Through synergistic regulation of CTAB morphology-directing agent and pH, monodisperse spherical gold nanoparticles with uniform particle size (16.8±3.27 nm) and excellent dispersibility (PDI<0.1) were successfully prepared. Their surface plasmon resonance (SPR) peak can be precisely controlled within the 750-850 nm range, significantly improving photothermal conversion efficiency (heating rate of 12.5℃ / min under 808 nm laser) and surface-enhanced Raman scattering (SERS) activity (signal enhancement of 10³-10). 4 (Times). Furthermore, as an environmental catalyst, it achieves a 99% degradation rate of phenol within 60 minutes; as a bioassay probe, its detection limit is as low as 0.01 pM; and as a SERS substrate for food safety detection, all demonstrating superior sensitivity and stability compared to existing technologies. Overall, this invention solves the core problems of traditional gold nanoparticles, such as toxicity, uncontrollable morphology, and limited functionality, through raw material innovation and process optimization.

[0092] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gold nanoparticle, characterized in that, The product comprises the following components by weight percentage: chloroauric acid 0.5-1.5%, quercetin 0.1-0.3%, chitosan 0.05-0.2%, hexadecyltrimethylammonium bromide 0.01-0.05%, and ultrapure water 97.2-98.3%. Among them, the degree of deacetylation of chitosan is ≥90%.

2. The gold nanoparticles according to claim 1, characterized in that, The molar ratio of chloroauric acid to quercetin is 1:3-1:5, the concentration of the chitosan solution is 1-2% (w / v), and the concentration of the hexadecyltrimethylammonium bromide solution is 0.5-2mM.

3. A method for preparing gold nanoparticles according to any one of claims 1 to 2, characterized in that, Includes the following steps: Step 1: Dissolve chloroauric acid in ultrapure water to prepare a 0.1-0.5 mM chloroauric acid solution; dissolve chitosan in a 1% acetic acid aqueous solution to prepare a 1-2% chitosan solution; dissolve quercetin in ethanol to prepare a 0.5-1.5 mM quercetin solution. Step 2: Mix chitosan solution with chloroauric acid solution; slowly add quercetin solution, the color of the system changes from pale yellow to wine red; let the reaction stand at room temperature for 2 hours to form spherical gold nanoparticles with uniform particle size; Step 3: Add CTAB solution, adjust pH to 8.0-8.5, stir and centrifuge to remove unreacted material, and resuspend in PBS buffer.

4. The method for preparing gold nanoparticles according to claim 3, characterized in that, Also includes: Step 4: Surface modification with targeted peptides or drug loading, with an encapsulation efficiency >85%.

5. The method for preparing gold nanoparticles according to claim 4, characterized in that, In step 3, the amount of CTAB added is 0.5-2 mM, and the pH of the reaction system is adjusted to 8.0-8.5 in real time using 0.1 M NaOH.

6. The method for preparing gold nanoparticles according to claim 5, characterized in that, In step 2, the chitosan solution and chloroauric acid solution are mixed under the following conditions: stirring at 300 rpm for 5 minutes.

7. The method for preparing gold nanoparticles according to claim 6, characterized in that, The spherical gold nanoparticles in step 2 have a size of 16.8 ± 3.27 nm.

8. The method for preparing gold nanoparticles according to claim 7, characterized in that, In step 3, the stirring conditions are 400 rpm for 30 minutes.

9. The method for preparing gold nanoparticles according to claim 8, characterized in that, In step 3, the centrifugation conditions are 6000 rpm for 10 minutes.

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