Gold nanoparticles and preparation method thereof

Abstract

The invention provides gold nanoparticles and a preparation method thereof. The preparation method of the gold nanoparticles comprises the steps that a chitosan solution and a chloroauric acid solution are mixed, then a quercetin solution is added, and the gold nanoparticles are obtained through in-situ reduction. The preparation method of the gold nanoparticles is green and environmentally friendly, quercetin is used as a reducing agent to replace a traditional chemical reducing agent, chitosan is used as a stabilizer to replace a synthetic surfactant, both quercetin and chitosan are biodegradable and nontoxic renewable resources, and pollution of toxic reagents to the environment is avoided. According to the method, a simple in-situ reduction method is used, the reaction can be completed under room-temperature and static conditions, and the method can be used for large-scale production; according to the method, the particle size of the gold nanoparticles can be changed by optimizing the dosage of chitosan, and the minimum particle size is 16.80 + / -3.27 nm; the gold nanoparticles prepared through the method are small in particle size, good in dispersity, good in stability, high in environment adaptability and easy to store for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of nano material synthesis, and in particular to gold nano particles and a preparation method thereof. Background Art

[0002] Gold nanoparticles are tiny particles composed of gold atoms, usually between 1 and 100 nanometers in size. Gold nanoparticles have remarkable optical properties, high specific surface area, chemical stability, biocompatibility and are easy to functionalize. They have been widely used in biomedicine, sensors, catalysis, electronics, environmental science and other fields. Traditional methods for preparing gold nanoparticles usually rely on chemical reducing agents, such as sodium citrate and sodium borohydride, which may not only be harmful to the environment, but also introduce impurities, affecting the performance of nanoparticles.

[0003] Based on the defects of the current method of preparing gold nanoparticles using chemical reducing agents, it is necessary to improve it. Summary of the invention

[0004] In view of this, the present invention provides a method for green synthesis of stable gold nanoparticles from quercetin and chitosan. The preparation method adopts the concept of green preparation to prepare gold nanoparticles of different particle sizes, good stability and good dispersibility, thus avoiding environmental pollution. The entire synthesis process is simple to operate, short in time, and easy to mass produce.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing gold nanoparticles, comprising the following steps: The chitosan solution and the chloroauric acid solution were mixed evenly, and then the quercetin solution was added to obtain gold nanoparticles by in-situ reduction.

[0006] Preferably, the chitosan solution is prepared by adding chitosan to an acetic acid solution having a volume concentration of 1 to 2% to obtain a chitosan solution; And / or, the preparation method of the chloroauric acid solution is: adding chloroauric acid into pure water to obtain the chloroauric acid solution; And / or, the preparation method of the quercetin solution is: adding quercetin into ethanol to obtain the quercetin solution.

[0007] Preferably, the mass concentration of the chitosan solution is 1-2%; And / or, the concentration of the chloroauric acid solution is 1-2 mM; And / or, the concentration of the quercetin solution is 2-7 mM.

[0008] Preferably, the volume ratio of the chitosan solution, the chloroauric acid solution and the quercetin solution is (0.4-2):(5-12):(1-2).

[0009] Preferably, each 100 mL of chitosan solution contains 1.5 g of chitosan; The concentration of the chloroauric acid solution is 1 mM; The concentration of the quercetin solution is 6 mM; The volume ratio of the chitosan solution, the chloroauric acid solution and the quercetin solution is 0.8:9:1.

[0010] Preferably, the chitosan solution and the chloroauric acid solution are evenly mixed, and then the quercetin solution is added and reacted at 20-25° C. for 1-300 min to obtain gold nanoparticles.

[0011] In a second aspect, the present invention also provides a gold nanoparticle prepared by the preparation method.

[0012] The gold nanoparticles and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art: 1. The preparation method of gold nanoparticles of the present invention is green and environmentally friendly. The method uses plant flavonoids (quercetin) as a reducing agent to replace traditional chemical reducing agents (such as sodium borohydride), and chitosan as a stabilizer to replace synthetic surfactants. Both are biodegradable, non-toxic and renewable resources, avoiding the pollution of toxic reagents to the environment; the method is simple to operate and takes a short time. The method uses a simple in-situ reduction method, and the reaction can be completed at room temperature and static conditions, and can be used for large-scale production; the method can change the particle size of gold nanoparticles by optimizing the amount of chitosan, and the minimum particle size is 16.80±3.27nm; the gold nanoparticles prepared by the method have a small particle size, good dispersibility, good stability, strong environmental adaptability, and are easy to store for a long time; the gold nanoparticles prepared by the method have a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 The UV-visible spectra at different reaction times in Comparative Example 1 are shown; Figure 2 The UV-visible spectra at different reaction times in Comparative Example 2 are shown; Figure 3The UV-visible spectra at different reaction times in Comparative Example 3 are shown; Figure 4 The UV-visible spectra at different reaction times in Comparative Example 4 are shown; Figure 5 The UV-visible spectra at different reaction times in Comparative Example 5 are shown; Figure 6 The UV-visible spectra at different reaction times in Comparative Example 6 are shown; Figure 7 The UV-Vis spectra at different reaction times in Example 1 are shown; Figure 8 The UV-Vis spectra at different reaction times in Example 2 are shown; Fig. 9 The UV-Vis spectra at different reaction times in Example 3; Fig.10 The UV-Vis spectra at different reaction times in Example 4 are shown; Fig.11 This is the TEM image of the gold nanoparticles obtained after reacting for 3 minutes in Comparative Example 5; Fig.12 The particle size statistical histogram of the gold nanoparticles obtained after reacting for 3 minutes in Comparative Example 5; Fig.13 This is a TEM image of the gold nanoparticles obtained after reacting for 90 minutes in Example 1; Fig.14 The particle size statistical histogram of the gold nanoparticles obtained after the reaction for 90 minutes in Example 1; Fig.15 This is a TEM image of the gold nanoparticles obtained after reacting for 180 min in Example 2; Fig.16 The particle size statistical histogram of the gold nanoparticles obtained after the reaction for 180 min in Example 2; Fig.17 This is a TEM image of the gold nanoparticles obtained after reacting for 180 min in Example 3; Fig.18 The particle size statistical histogram of the gold nanoparticles obtained after the reaction for 180 min in Example 3; Fig.19 This is a TEM image of the gold nanoparticles obtained after reacting for 180 min in Example 4; Fig. 20 The particle size statistical histogram of the gold nanoparticles obtained after the reaction for 180 min in Example 4; Fig.21 The gold nanoparticles obtained after reacting for 3 minutes according to the method in Comparative Example 5 are UV-Vis spectra monitored and analyzed by UV-Vis at different temperatures; Fig. 22 The gold nanoparticles obtained after reacting for 90 minutes in Example 1 are UV-Vis spectra monitored and analyzed by UV-Vis at different temperatures; Fig.23 The gold nanoparticles obtained after reacting for 180 min in Example 2 are UV-Vis spectra monitored and analyzed by UV-Vis at different temperatures; Fig.24 The gold nanoparticles obtained after reacting for 180 min in Example 3 are UV-Vis spectra monitored and analyzed by UV-Vis at different temperatures; Fig.25 The gold nanoparticles obtained after reacting for 180 min in Example 4 are UV-Vis spectra monitored and analyzed by UV-Vis at different temperatures; Fig.26 The gold nanoparticles obtained after reacting for 3 minutes according to the method in Comparative Example 5 are UV-Vis spectra monitored and analyzed by UV-Vis at different pH values; Fig. 27 The gold nanoparticles obtained after reacting for 90 minutes in Example 1 are UV-Vis spectra monitored and analyzed by UV-Vis at different pH values; Fig.28 The gold nanoparticles obtained after reacting for 180 min in Example 2 are UV-Vis spectra monitored and analyzed by UV-Vis at different pH values; Fig.29 The gold nanoparticles obtained after reacting for 180 min in Example 3 are UV-Vis spectra monitored and analyzed by UV-Vis at different pH values; Fig.30 The gold nanoparticles obtained after reacting for 180 min in Example 4 are UV-Vis spectra monitored and analyzed by UV-Vis at different pH values; Fig.31 The gold nanoparticles obtained after reacting for 3 minutes according to the method in Comparative Example 5 are UV-Vis spectra monitored and analyzed by UV-Vis under different volumes of NaCl aqueous solution; Fig.32 The gold nanoparticles obtained after reacting for 90 minutes in Example 1 are UV-Vis spectra monitored and analyzed by UV-Vis in different volumes of NaCl aqueous solution; Fig.33The gold nanoparticles obtained after the reaction for 180 min in Example 2 are UV-Vis spectra monitored and analyzed by UV-Vis in different volumes of NaCl aqueous solution; Fig.34 The gold nanoparticles obtained after reacting for 180 min in Example 3 are UV-Vis spectra monitored and analyzed by UV-Vis in different volumes of NaCl aqueous solution; Fig.35 The gold nanoparticles obtained after reacting for 180 min in Example 4 are UV-Vis spectra monitored and analyzed by UV-Vis in different volumes of NaCl aqueous solution; Fig.36 The gold nanoparticles obtained after reacting for 3 minutes according to the method in Comparative Example 5 are UV-Vis spectra monitored and analyzed by UV-Vis at different standing times; Fig.37 The gold nanoparticles obtained after reacting for 90 minutes in Example 1 are UV-Vis spectra monitored and analyzed by UV-Vis at different standing times; Fig.38 The gold nanoparticles obtained after reacting for 180 min in Example 2 are UV-Vis spectra monitored and analyzed at different standing times; Fig.39 The gold nanoparticles obtained after reacting for 180 min in Example 3 are UV-Vis spectra monitored and analyzed by UV-Vis at different standing times; Fig.40 The gold nanoparticles obtained after reacting for 180 min in Example 4 are UV-Vis spectra monitored and analyzed by UV-Vis at different standing times. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0017] The present application provides a method for preparing gold nanoparticles, comprising the following steps: The chitosan solution and the chloroauric acid solution were mixed evenly, and then quercetin (structural formula C 15 H 10 O7) solution and in situ reduction to obtain gold nanoparticles.

[0018] The preparation method of the gold nanoparticles of the present invention comprises the following steps: uniformly mixing non-toxic and degradable chitosan as a dispersant and a stabilizer with a certain amount of chloroauric acid, and then adding quercetin as a reducing agent to prepare gold nanoparticles of different particle sizes through in-situ reduction. The entire preparation process is green, simple, and short in time, and the synthesized gold nanoparticles have small particle sizes, good dispersibility, and good stability.

[0019] In some embodiments, the chitosan solution is prepared by adding chitosan to an acetic acid solution having a volume concentration of 1 to 2% to obtain a chitosan solution; The preparation method of the chloroauric acid solution is as follows: adding chloroauric acid into pure water to obtain the chloroauric acid solution; The preparation method of the quercetin solution is as follows: quercetin is added into ethanol to obtain the quercetin solution.

[0020] In some embodiments, the mass concentration of the chitosan solution is 1-2%; In some embodiments, the concentration of the chloroauric acid solution is 1-2 mM; In some embodiments, the concentration of the quercetin solution is 2-7 mM, for example, the concentration of the quercetin solution is 2 mM, 3 mM, 4 mM, 5 mM, 6 mM, or 7 mM.

[0021] In some embodiments, the volume ratio of chitosan solution, chloroauric acid solution and quercetin solution is (0.4~2):(5~12):(1~2); preferably, the volume ratio of chitosan solution, chloroauric acid solution and quercetin solution is 0.8mL:9mL:1mL, the concentration of chitosan solution is 1.5% (w / v, i.e., 1.5 grams of chitosan is contained in every 100 mL of chitosan solution), the concentration of chloroauric acid solution is 1mM, and the concentration of quercetin solution is 6mM. In some embodiments, the concentration of the chloroauric acid solution is 1 mM.

[0022] In some embodiments, a chitosan solution is mixed with a chloroauric acid solution, and then a quercetin solution is added, and the mixture is reacted at 20-25° C. for 1-300 min to obtain gold nanoparticles.

[0023] The method for preparing gold nanoparticles of the present invention comprises quercetin as a reducing agent, chloroauric acid as a precursor, and chitosan as a stabilizer in the reaction system; the method is green and environmentally friendly, and uses plant flavonoids (quercetin) as a reducing agent to replace traditional chemical reducing agents (such as sodium borohydride), and uses chitosan as a stabilizer to replace synthetic surfactants, both of which are biodegradable, non-toxic and renewable resources, thus avoiding the pollution of the environment by toxic reagents; the method is simple to operate and takes a short time. The method uses a simple in-situ reduction method, and the reaction can be completed at room temperature and under static conditions, and can be used for large-scale production; the method can change the particle size of gold nanoparticles by optimizing the amount of chitosan, and the minimum particle size is 16.80±3.27nm; the gold nanoparticles prepared by the method have a small particle size, good dispersibility, good stability, strong environmental adaptability, and are easy to store for a long time; the gold nanoparticles prepared by the method have a wide range of applications.

[0024] Based on the same inventive concept, the present invention also provides a gold nanoparticle prepared by the above-mentioned preparation method.

[0025] The gold nanoparticles and preparation methods of the present application are further described below with specific examples. This section further describes the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0026] In the figure below, 2~7mM Qu means that the concentration of quercetin solution is 2~7mM, and 1mM HAuCl4 means that the concentration of chloroauric acid solution is 1mM; in the figure below, 6 mM Qu means that the concentration of quercetin solution is 6mM, 1mM HAuCl4 means that the concentration of chloroauric acid solution is 1mM, and 0.4~1mL 1.5% chit means that the concentration of chitosan solution in Examples 1~4 is 1.5%, and the volume is 0.4~1mL.

[0027] Example 1 The present invention provides a method for preparing gold nanoparticles, comprising the following steps: 0.4 mL of 1.5% (w / v, i.e., 1.5 g of chitosan per 100 mL of chitosan solution) chitosan solution (solvent: 1% volume concentration of acetic acid solution) was mixed evenly with 9 mL of 1 mM chloroauric acid solution (solvent: pure water), and then 1 mL of 6 mM quercetin solution (solvent: ethanol) was added to react at room temperature (20-25°C) to obtain gold nanoparticles by in-situ reduction; and the UV-visible spectra were monitored at different reaction times (1 min-120 min). The results are shown in Figure 2. Figure 7 shown.

[0028] Example 2 The present application example provides a method for preparing gold nanoparticles, which is the same as Example 1, except that 0.4 mL of chitosan solution with a concentration of 1.5% is replaced by 0.6 mL of chitosan solution with a concentration of 1.5%, and the other process parameters are exactly the same as those in Example 1. The UV-visible spectra are monitored at different reaction times (1 min to 240 min). The results are as follows: Figure 8 shown.

[0029] Example 3 The present application example provides a method for preparing gold nanoparticles, which is the same as Example 1, except that 0.4 mL of chitosan solution with a concentration of 1.5% is replaced by 0.8 mL of chitosan solution with a concentration of 1.5%, and the other process parameters are exactly the same as those in Example 1. The UV-visible spectra are monitored at different reaction times (1 min to 240 min). The results are as follows: Fig. 9 shown.

[0030] Example 4 The present application example provides a method for preparing gold nanoparticles, which is the same as Example 1, except that 0.4 mL of a 1.5% chitosan solution is replaced with 1 mL of a 1.5% chitosan solution, and the remaining process parameters are exactly the same as those in Example 1. The UV-visible spectrum results are monitored at different reaction times (1 min to 240 min). Fig.10 shown.

[0031] Comparative Example 1 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: Add 1 mL of 2 mM quercetin solution (solvent: ethanol) to 9 mL of 1 mM chloroauric acid solution (solvent: pure water), react at room temperature (20-25°C), and reduce to obtain gold nanoparticles; and monitor the UV-visible spectrum results at different reaction times (1 min ~ 70 min), such as Figure 1 shown.

[0032] Comparative Example 2 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: The preparation method of gold nanoparticles provided in this comparative example is the same as that in comparative example 1, except that 1 mL, 2 mM quercetin solution is replaced by 1 mL, 3 mM quercetin solution, and the other process parameters are exactly the same as those in comparative example 1, and the UV-visible spectrum results are monitored at different reaction times (1 min to 30 min), as shown in FIG. Figure 2 shown.

[0033] Comparative Example 3 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: The preparation method of gold nanoparticles provided in this comparative example is the same as that in comparative example 1, except that 1 mL, 2 mM quercetin solution is replaced by 1 mL, 4 mM quercetin solution, and the other process parameters are exactly the same as those in comparative example 1, and the UV-visible spectrum results are monitored at different reaction times (1 min to 20 min), as shown in FIG. Figure 3 shown.

[0034] Comparative Example 4 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: The preparation method of gold nanoparticles provided in this comparative example is the same as that in comparative example 1, except that 1 mL, 2 mM quercetin solution is replaced by 1 mL, 5 mM quercetin solution, and the other process parameters are exactly the same as those in comparative example 1, and the UV-visible spectrum results are monitored at different reaction times (1 min to 5 min), as shown in FIG. Figure 4 shown.

[0035] Comparative Example 5 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: The preparation method of gold nanoparticles provided in this comparative example is the same as that in comparative example 1, except that 1 mL, 2 mM quercetin solution is replaced by 1 mL, 6 mM quercetin solution, and the other process parameters are exactly the same as those in comparative example 1, and the UV-visible spectrum results are monitored at different reaction times (1 min to 5 min), as shown in FIG. Figure 5 shown.

[0036] Comparative Example 6 This comparative example provides a method for preparing gold nanoparticles, comprising the following steps: The preparation method of gold nanoparticles provided in this comparative example is the same as that in comparative example 1, except that 1 mL, 2 mM quercetin solution is replaced by 1 mL, 7 mM quercetin solution, and the other process parameters are exactly the same as those in comparative example 1, and the UV-visible spectrum results are monitored at different reaction times (1 min to 5 min), as shown in FIG. Figure 6 shown.

[0037] The color of the solution changes from light yellow to purple, indicating the formation of gold nanoparticles. The growth and stability of the gold nanoparticles are observed by UV spectrophotometer. The morphology, dispersion and particle size of the gold nanoparticles are further characterized by TEM. Specifically, the solution after the reaction is completed is monitored and analyzed by UV-Vis, using a 1 cm quartz cuvette to scan and record the absorption spectrum in the range of 400-800 nm. Figures 1 to 6 It can be seen that the maximum UV absorption intensity is observed at a wavelength of about 540nm, and the time for the reaction to be basically complete is 60min, 20min, 10min, 3min, 3min, and 3min respectively; therefore, the concentration of quercetin and chloroauric acid is selected as n(Qu):n(Au3 + )=0.6:0.9 (i.e., using 9 mL, 1 mM chloroauric acid solution and 1 mL, 6 mM quercetin solution) as the optimal concentration for further synthesis of stable gold nanoparticles.

[0038] from Figures 7-10 It can be seen that the maximum ultraviolet absorption intensity was observed at a wavelength of about 540nm, and the time for the reaction to be basically complete was 90 min, 180 min, 180 min and 180 min respectively.

[0039] Figures 11-12 They are the TEM image and particle size statistical histogram of the gold nanoparticles obtained after reacting for 3 minutes in Comparative Example 5.

[0040] Figures 13 and 14 They are respectively the TEM image and particle size statistical histogram of the gold nanoparticles obtained after reacting for 90 minutes in Example 1.

[0041] Figures 15 and 16They are respectively the TEM image and particle size statistical histogram of the gold nanoparticles obtained after reacting for 180 min in Example 2.

[0042] Figures 17 and 18 They are respectively the TEM image and particle size statistical histogram of the gold nanoparticles obtained after reacting for 180 min in Example 3.

[0043] Figures 19 and 20 They are respectively the TEM image and particle size statistical histogram of the gold nanoparticles obtained after reacting for 180 min in Example 4.

[0044] from Figures 11 to 20 It can be seen that the gold nanoparticles modified with chitosan (Chit-AuNPs) are evenly dispersed, while the gold nanoparticles without chitosan modification have obvious agglomeration ( Figures 11-12 The average particle size of the gold nanoparticles (Chit-AuNPs) modified by chitosan in Examples 1 to 4 first decreases and then increases with the increase of the chitosan dosage. When the chitosan dosage is 0.8 ml, the average particle size of the gold nanoparticles is the smallest, which is 16.80±3.27 nm.

[0045] The gold nanoparticles obtained after reacting for 3 min according to the method in Comparative Example 5 were monitored and analyzed by UV-Vis at different temperatures (20°C, 40°C, 60°C, and 80°C). The results are as follows Fig.21 shown.

[0046] The gold nanoparticles obtained after 90 min of reaction in Example 1 were monitored and analyzed by UV-Vis at different temperatures (20°C, 40°C, 60°C, and 80°C). The results are as follows Fig. 22 shown.

[0047] The gold nanoparticles obtained after 180 min of reaction in Example 2 were monitored and analyzed by UV-Vis at different temperatures (20°C, 40°C, 60°C, and 80°C). The results are as follows Fig.23 shown.

[0048] The gold nanoparticles obtained after 180 min of reaction in Example 3 were monitored and analyzed by UV-Vis at different temperatures (20°C, 40°C, 60°C, and 80°C). The results are as follows Fig.24 shown.

[0049] The gold nanoparticles obtained after 180 min of reaction in Example 4 were monitored and analyzed by UV-Vis at different temperatures (20°C, 40°C, 60°C, and 80°C). The results are as follows Fig.25 shown.

[0050] from Figures 21 to 25As can be seen from the figure, the gold nanoparticles (AuNPs 0 ), the absorption peak gradually decreases with the increase of temperature, and the peak value basically disappears at 60℃, which shows that AuNPs 0 The agglomeration is obvious and the gold nanoparticles are not stable enough, while the absorption peak of Chit-AuNPs in Examples 1 to 4 gradually increases with the increase of temperature, indicating that the gold nanoparticles have no obvious agglomeration and are relatively stable.

[0051] The gold nanoparticles were obtained after reacting for 3 min according to the method in Comparative Example 5, and the pH of the solution after the reaction was adjusted to 2.67-11 (adjusted by using NaOH or HCl), and UV-Vis was used for monitoring and analysis at different pH values. The results are as follows Fig.26 shown.

[0052] The gold nanoparticles obtained after 90 min of reaction in Example 1 were adjusted to a pH of 3.6 to 11 (using NaOH or HCl) and UV-Vis monitoring and analysis was performed at different pH values. The results are as follows: Fig. 27 shown.

[0053] The gold nanoparticles obtained after 180 min of reaction in Example 2 were adjusted to a pH of 3.9 to 11 (using NaOH or HCl) and UV-Vis monitoring and analysis was performed at different pH values. The results were as follows: Fig.28 shown.

[0054] The gold nanoparticles obtained after 180 min of reaction in Example 3 were adjusted to a pH of 4-11 (using NaOH or HCl) and UV-Vis monitoring and analysis was performed at different pH values. The results were as follows: Fig.29 shown.

[0055] The gold nanoparticles obtained after 180 min of reaction in Example 4 were adjusted to a pH of 4.1 to 11 (using NaOH or HCl), and UV-Vis monitoring and analysis were performed at different pH values. The results were as follows: Fig.30 shown.

[0056] from Figures 26 to 30 It can be seen that AuNPs 0 There was no significant change in the maximum UV absorption intensity of AuNPs and Chit-AuNPs, indicating that pH had little effect on gold nanoparticles.

[0057] According to the method in Comparative Example 5, the gold nanoparticles obtained after reacting for 3 minutes were taken, and 3 mL of the solution containing gold nanoparticles was added with 0 μL, 50 μL, 100 μL, and 200 μL of 0.5 M NaCl aqueous solution, respectively. UV-Vis monitoring and analysis were performed under different volumes of NaCl aqueous solution. The results are as follows: Fig.31 shown.

[0058] According to the gold nanoparticles obtained after 90 min of reaction in Example 1, 3 mL of the solution containing gold nanoparticles was taken and 0 μL, 50 μL, 100 μL, and 200 μL of 0.5 M NaCl aqueous solution were added respectively. UV-Vis monitoring and analysis were performed under different volumes of NaCl aqueous solution. The results are as follows: Fig.32 shown.

[0059] According to the gold nanoparticles obtained after 180 min of reaction in Example 2, 3 mL of the solution containing gold nanoparticles was taken and 0 μL, 50 μL, 100 μL, and 200 μL of 0.5 M NaCl aqueous solution were added respectively. UV-Vis monitoring and analysis were performed under different volumes of NaCl aqueous solution. The results are as follows: Fig.33 shown.

[0060] According to the gold nanoparticles obtained after 180 min of reaction in Example 3, 3 mL of the solution containing gold nanoparticles was taken and 0 μL, 50 μL, 100 μL, and 200 μL of 0.5 M NaCl aqueous solution were added respectively. UV-Vis monitoring and analysis were performed under different volumes of NaCl aqueous solution. The results are as follows: Fig.34 shown.

[0061] According to the gold nanoparticles obtained after 180 min of reaction in Example 4, 3 mL of the solution containing gold nanoparticles was taken and 0 μL, 50 μL, 100 μL, and 200 μL of 0.5 M NaCl aqueous solution were added respectively. UV-Vis monitoring and analysis were performed under different volumes of NaCl aqueous solution. The results are as follows: Fig.35 shown.

[0062] from Figures 31 to 35 As can be seen from the figure, the gold nanoparticles (AuNPs 0 ) and the maximum ultraviolet absorption intensity of Chit-AuNPs prepared in Examples 1 to 4 decreased, but the decrease in the maximum ultraviolet absorption intensity of Chit-AuNPs was lower than that of AuNPs 0 The decrease in the maximum UV absorption intensity.

[0063] The gold nanoparticles were obtained after reacting for 3 min according to the method in Comparative Example 5, and then left to stand at room temperature (20-25°C) for 6-960 h. UV-Vis monitoring and analysis were performed at different standing times. The results are as follows: Fig.36 shown.

[0064] The gold nanoparticles obtained after 90 min of reaction in Example 1 were allowed to stand at room temperature (20-25° C.) for 6-960 h, and UV-Vis monitoring and analysis were performed at different standing times. The results were as follows: Fig.37 shown.

[0065] The gold nanoparticles obtained after 180 min of reaction in Example 2 were allowed to stand at room temperature (20-25° C.) for 6-960 h, and UV-Vis monitoring and analysis were performed at different standing times. The results were as follows: Fig.38 shown.

[0066] The gold nanoparticles obtained after 180 min of reaction in Example 3 were allowed to stand at room temperature (20-25° C.) for 6-960 h, and UV-Vis monitoring and analysis were performed at different standing times. The results were as follows: Fig.39 shown.

[0067] The gold nanoparticles obtained after 180 min of reaction in Example 4 were allowed to stand at room temperature (20-25° C.) for 6-960 h, and UV-Vis monitoring and analysis were performed at different standing times. The results were as follows: Fig.40 shown.

[0068] from Figures 36 to 40 It can be seen that in Comparative Example 5, AuNPs 0 The maximum UV absorption intensity of AuNPs decreased significantly over time, and the peak wavelength tended to red shift, indicating that 0 There is obvious agglomeration, while the maximum ultraviolet absorption intensity of Chit-AuNPs in Examples 1 to 4 shows a trend of first increasing and then decreasing, and the peak wavelength has no obvious change. These results show that the addition of chitosan improves the stability of gold nanoparticles.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing gold nanoparticles, characterized in that: The following steps are involved: The chitosan solution and the chloroauric acid solution were mixed evenly, and then the quercetin solution was added to obtain gold nanoparticles by in-situ reduction.

2. The method for preparing gold nanoparticles according to claim 1, characterized in that: The chitosan solution is prepared by adding chitosan to an acetic acid solution having a volume concentration of 1-2% to obtain a chitosan solution; And / or, the preparation method of the chloroauric acid solution is: adding chloroauric acid into pure water to obtain the chloroauric acid solution; And / or, the preparation method of the quercetin solution is: adding quercetin into ethanol to obtain the quercetin solution.

3. The method for preparing gold nanoparticles according to claim 1, characterized in that: The mass concentration of the chitosan solution is 1-2%; And / or, the concentration of the chloroauric acid solution is 1-2 mM; And / or, the concentration of the quercetin solution is 2-7 mM.

4. The method for preparing gold nanoparticles according to claim 3, characterized in that: The volume ratio of the chitosan solution, the chloroauric acid solution and the quercetin solution is (0.4-2):(5-12):(1-2).

5. The method for preparing gold nanoparticles according to claim 3, characterized in that: Each 100 mL of chitosan solution contains 1.5 g of chitosan; The concentration of the chloroauric acid solution is 1 mM; The concentration of the quercetin solution is 6 mM; The volume ratio of the chitosan solution, the chloroauric acid solution and the quercetin solution is 0.8:9:

1.

6. The method for preparing gold nanoparticles according to claim 1, characterized in that: The chitosan solution and the chloroauric acid solution were mixed evenly, and then the quercetin solution was added, and the mixture was reacted at 20-25° C. for 1-300 min to obtain gold nanoparticles.

7. A gold nanoparticle, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 6.

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