Preparation method and application of noble metal nanoparticle / carbon-based nanoscale enzyme

Abstract

The application belongs to the technical field of nano-enzyme, and particularly relates to a preparation method and application of noble metal nanoparticle / carbon-based nano-enzyme. The melamine-cyanuric acid supramolecular aggregate is used as a template, nitrogen-containing small molecule gas is generated by decomposition in a high-temperature pyrolysis process, which is beneficial to the formation of a porous structure, and the removal process of the template can be effectively avoided. In addition, the high nitrogen content of the supramolecular aggregate can realize the doping of nitrogen atoms in the carbon material, and the whole operation process is simple. Then, the nitrogen-doped porous carbon is used as a carrier, the carbon surface nitrogen atoms can effectively stabilize the gold nanoparticles to ensure the size of the nanoparticles and prevent aggregation, the large specific surface area of the porous carbon can provide effective support for the loading of the gold nanoparticles and will not limit the activity of the gold nanoparticles, and the obtained composite material has enhanced peroxidase activity, wide linear range and high selectivity for H2O2 detection.

Description

Technical Field

[0001] This invention belongs to the field of nanoenzyme technology, and specifically relates to a method for preparing noble metal nanoparticles / carbon-based nanoenzymes and their applications. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important small biomolecule present in living organisms, and abnormal levels may be associated with various diseases, such as myocardial infarction, Alzheimer's disease, Parkinson's disease, and cancer. Highly sensitive detection of H2O2 is crucial for initial disease screening. Existing methods for H2O2 detection include chemiluminescence, fluorescence, titration, and electrochemical analysis. Among these, electrochemical analysis offers advantages such as high sensitivity, good selectivity, ease of operation, and low cost. Electrochemical sensors used for H2O2 determination can be categorized into enzyme-free and enzyme-involved sensors. Enzyme-involved sensors often utilize natural horseradish peroxidase, which exhibits high sensitivity and selectivity for H2O2. Natural enzymes are large biomolecules with high biological activity and selectivity. However, natural enzymes suffer from high purification costs, environmental sensitivity, susceptibility to denaturation and inactivation, and long preparation cycles, limiting their widespread application in practical applications. With the development of nanoscience and nanomaterials, nanomaterials with enzyme activity (nanozymes) have attracted widespread attention due to their unique physicochemical properties and bioactivity comparable to natural enzymes.

[0003] Currently, over 300 nanomaterials have been reported to possess intrinsic enzymatic activity. While significant progress has been made in the field of nanozymes, there is still considerable room for improvement in their catalytic activity and substrate selectivity. Among the many materials exhibiting nanozyme activity, noble metal nanomaterials have attracted increasing attention due to their unique high catalytic activity and strong reaction stability. However, small-sized noble metal nanomaterials often suffer from aggregation during synthesis, affecting their stability and limiting their widespread application. Modifying the surface of noble metal nanoparticles with biomolecules and ligands can stabilize them, but surface coatings can also limit the catalytic activity of the noble metal nanoparticles. Summary of the Invention

[0004] To address or partially address the aforementioned problems, this invention proposes a method for preparing noble metal nanoparticles / carbon-based nanozymes, the method comprising the following steps:

[0005] Melamine and cyanuric acid were dissolved in dimethyl sulfoxide, respectively, and then the solutions were mixed to prepare melamine-cyanuric acid supramolecular aggregates.

[0006] Glucose and the melamine-cyanuric acid supramolecular aggregate were mixed, and nitrogen-doped porous carbon was prepared in a high-temperature pure nitrogen atmosphere.

[0007] Noble metal nanoparticles / carbon-based nanozymes were prepared by adding HAuCl4 to the dispersion of nitrogen-doped porous carbon and then adding NaBH4 solution dropwise.

[0008] Further, the step of dissolving melamine and cyanuric acid in dimethyl sulfoxide, and then mixing the solutions to prepare melamine-cyanuric acid supramolecular aggregates includes the following steps:

[0009] Melamine was dissolved in dimethyl sulfoxide and sonicated to obtain a colorless, clear, and transparent solution A. Cyanuric acid was dissolved in dimethyl sulfoxide and sonicated to obtain a colorless, clear, and transparent solution B.

[0010] Under stirring conditions, solution B is poured into solution A, and a white precipitate appears. Stirring continues, and the white precipitate is filtered using an organic solvent microporous filter membrane.

[0011] The white filtered product was placed in a vacuum drying oven and dried at 50-80℃ to obtain melamine-cyanuric acid supramolecular aggregates.

[0012] Further, the step of mixing glucose and the melamine-cyanuric acid supramolecular aggregate, and then preparing nitrogen-doped porous carbon in a high-temperature pure nitrogen atmosphere includes the following steps:

[0013] Glucose and the melamine-cyanuric acid supramolecular aggregates were ground in a mortar to obtain a homogeneous mixture;

[0014] The mixture was placed in a high-temperature tube furnace and heated to 700°C at a heating rate of 2.5°C / min in a pure nitrogen atmosphere. After being held at 700°C for 2 hours, it was naturally cooled to room temperature to obtain nitrogen-doped porous carbon.

[0015] Further, the step of adding HAuCl4 to the dispersion of nitrogen-doped porous carbon and then adding NaBH4 solution dropwise to prepare noble metal nanoparticles / carbon-based nanozymes includes the following steps:

[0016] The nitrogen-doped porous carbon was dispersed in deionized water and ultrasonicated to obtain a dispersion.

[0017] After adding HAuCl4 to the dispersion and stirring, a nitrogen-doped porous carbon dispersion containing HAuCl4 was obtained.

[0018] NaBH4 solution was added dropwise to a nitrogen-doped porous carbon dispersion containing HAuCl4. After stirring, the product was centrifuged and washed with deionized water. The washed product was then dried to obtain noble metal nanoparticles / carbon-based nanozymes.

[0019] Furthermore, the solubility ratio of melamine to dimethyl sulfoxide is 1 g: 40 mL; the solubility ratio of cyanuric acid to dimethyl sulfoxide is 2.04 g: 40 mL.

[0020] Furthermore, the mass ratio of glucose to melamine-cyanuric acid supramolecular aggregate is 0.25g:2.0g.

[0021] Furthermore, the mixing ratio of the nitrogen-doped porous carbon and deionized water is 1-2 mg: 1 mL;

[0022] The nitrogen-doped porous carbon and HAuCl4 were fed in a ratio of 10 mg to 5 mL, wherein the concentration of HAuCl4 was 3-12 mM.

[0023] Secondly, the present invention proposes a noble metal nanoparticle / carbon-based nanozyme prepared by the preparation method described above, wherein the noble metal nanoparticle / carbon-based nanozyme includes HAuCl4 nanoparticles and nitrogen-doped porous carbon.

[0024] Thirdly, the present invention proposes an electrode modified with noble metal nanoparticles / carbon-based nanozymes, the electrode comprising noble metal nanoparticles / carbon-based nanozymes prepared by the aforementioned preparation method and the electrode.

[0025] Fourthly, this invention proposes the application of noble metal nanoparticles / carbon-based nanozymes in biodetection, wherein the biodetection includes the detection of hydrogen peroxide content in organisms.

[0026] The beneficial effects of this invention are:

[0027] This invention uses melamine-cyanuric acid supramolecular aggregates as templates. During high-temperature pyrolysis, these aggregates decompose to generate nitrogen-containing small molecule gases, which is beneficial for the formation of porous structures and effectively avoids the template removal process. Furthermore, the high nitrogen content (49.4%) of the supramolecular aggregates allows for nitrogen atom doping in carbon materials. Compared to traditional chemical vapor deposition and nitrogen plasma treatment methods, this is less expensive and simpler to operate. Compared to hard template methods, this invention is simpler and yields higher output. The preparation process is simpler and more controllable, with high reproducibility, and it eliminates the need for corrosive precursors, making mass production more feasible. Simultaneously, this invention uses nitrogen-doped porous carbon as a carrier. The nitrogen atoms on the carbon surface effectively stabilize gold nanoparticles, ensuring their size and preventing aggregation. The large specific surface area of ​​the porous carbon provides effective support for the loading of gold nanoparticles without limiting their activity. The resulting composite material exhibits enhanced peroxidase activity and a wide linear range (0.2-7000 μM) and high selectivity for H2O2 detection.

[0028] The noble metal nanoparticles / carbon-based nanozymes prepared by this invention have good stability and can replace natural horseradish peroxidase for analysis and detection.

[0029] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart of a method for preparing noble metal nanoparticles / carbon-based nanozymes proposed in this invention is shown;

[0032] Figure 2 The following is a scanning electron microscope image of the melamine-cyanuric acid supramolecular aggregates synthesized in an embodiment of the present invention;

[0033] Figure 3 The molecular structure of the melamine-cyanuric acid supramolecular aggregate synthesized in the embodiments of the present invention is shown.

[0034] Figure 4 The image shown is a scanning electron microscope image of the synthesized NPC in an embodiment of the present invention;

[0035] Figure 5 Electron micrographs of the synthesized AuNPs / NPCs in this embodiment of the invention are shown; where a is a scanning electron microscope image, b is a transmission electron microscope image, and c is a high-resolution transmission electron microscope image.

[0036] Figure 6 The X-ray diffraction patterns of synthesized AuNPs / NPCs and NPCs in embodiments of the present invention are shown.

[0037] Figure 7 The CV diagrams of the catalytic response of H2O2 to different concentrations of HAuCl4 during the synthesis process in the embodiments of the present invention are shown.

[0038] Figure 8The diagram shows the peroxidase activity analysis under different conditions in the embodiments of the present invention; where a is a comparison diagram of enzyme activity of different materials, and b is a comparison diagram of the activities of AuNPs / NPC catalyzed by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD), and 3,3',5,5'-tetramethylbenzidine (TMB);

[0039] Figure 9 The CV plots of bare GCE, NPC / GCE and AuNPs / NPC / GCE catalyzing 5mM H2O2 are shown in the embodiments of the present invention;

[0040] Figure 10 The figures show the amperometric it curve and linear relationship graph for detecting H2O2 in an embodiment of the present invention; where a is the amperometric it curve and b is the linear relationship graph.

[0041] Figure 11 The test results of time stability and operational stability of AuNPs / NPC / GCE in the embodiments of the present invention are shown in the figure; where a is the time stability test result figure and b is the operational stability test result figure;

[0042] Figure 12 The diagram shows a test plot of the selectivity of AuNPs / NPC / CGE using the Ampere-it curve method in an embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The purpose of this invention is to provide a method for preparing noble metal nanoparticles / carbon-based nanozymes. Using melamine-cyanuric acid supramolecular aggregates and glucose as precursors, nitrogen-doped porous carbon (NPC) is obtained through one-step pyrolysis. Using NPC as a substrate, HAuCl4 is then added and a one-step reduction method is used to obtain noble metal nanoparticles / carbon-based nanozymes (AuNPs / NPC) loaded with gold nanoparticles.

[0045] The main steps of the preparation method are as follows: Figure 1 As shown, it includes:

[0046] Step 1: Melamine and cyanuric acid are dissolved in dimethyl sulfoxide separately, and then the solutions are mixed to prepare melamine-cyanuric acid supramolecular aggregates;

[0047] Step 2: Glucose and the melamine-cyanuric acid supramolecular aggregate are mixed, and NPC is prepared in a high-temperature pure nitrogen atmosphere after mixing.

[0048] Step 3: Add HAuCl4 to the dispersion of nitrogen-doped porous carbon and add NaBH4 solution dropwise to prepare AuNPs / NPC.

[0049] To more clearly illustrate the preparation method and application of the noble metal nanoparticles / carbon-based nanozymes proposed in this invention, the following detailed description is provided in conjunction with specific embodiments.

[0050] Example 1: Preparation of noble metal nanoparticles / carbon-based nanozymes (AuNPs / NPCs)

[0051] Step 1: Dissolve 2.0 g of melamine in 80 mL of dimethyl sulfoxide and sonicate until homogeneous to obtain a colorless, clear, and transparent solution A. Dissolve 2.04 g of cyanuric acid in 40 mL of dimethyl sulfoxide and sonicate until homogeneous to obtain a colorless, clear, and transparent solution B. Then, under stirring, pour solution B into solution A; a white precipitate immediately appears. Continue stirring for 20 min. Filter the formed white precipitate through a 0.45 μm organic solvent microporous membrane. Wash the white precipitate with 80 mL of ethanol and filter again. Place the white filtered product in a vacuum drying oven at 60 °C and dry overnight to obtain melamine-cyanuric acid supramolecular aggregates.

[0052] The melamine-cyanuric acid supramolecular aggregates obtained in step one were subjected to scanning electron microscopy (SEM) analysis, and the SEM images are shown below. Figure 2 As shown in the figure, the melamine-cyanuric acid supramolecular aggregates are composed of stacked nanosheets exhibiting a rose-like morphology, with a size of approximately 2 μm and a uniform distribution; their molecular structure formula is as follows. Figure 3 As shown.

[0053] Step 2: Take 0.25g of glucose and 2.0g of the melamine-cyanuric acid supramolecular aggregate prepared in Step 1, grind them in a mortar for 30 minutes to obtain a homogeneous mixture. Place the mixture in a high-temperature tube furnace, purge the air from the tube furnace with high-purity nitrogen for half an hour. Then, heat the mixture to 700℃ in a high-purity nitrogen atmosphere at a heating rate of 2.5℃ / min, maintain the temperature at 700℃ for 2 hours, and then allow it to cool naturally to room temperature to obtain NPC.

[0054] The NPC prepared in step two was subjected to scanning electron microscopy, and the test results are as follows: Figure 4As shown, NPC exhibits a porous red blood cell-like structure.

[0055] Step 3: Preparation of AuNPs / NPCs via wet chemical method;

[0056] 10.0 mg of the NPC prepared in step 2 was dispersed in 10 mL of deionized water and sonicated for 30 min to obtain a homogeneous dispersion. Then, 5 mL of HAuCl4 (6 mM) was added to the dispersion and stirred for 20 min. 2 mL of freshly prepared 15 mg / mL NaBH4 solution was added dropwise to the NPC dispersion containing HAuCl4, and stirring was continued for 90 min. After 90 min, the product was centrifuged at 10,000 rpm and washed five times with deionized water. The washed product was then placed in a vacuum drying oven at 60 °C for 8 h to obtain AuNPs / NPC.

[0057] The AuNPs / NPCs prepared in this embodiment were subjected to scanning electron microscopy and transmission electron microscopy tests; the electron microscopy images are shown below. Figure 5 As shown, A is a scanning electron microscope image, which shows that gold nanoparticles are uniformly distributed on the NPC surface; B is a transmission electron microscope image, which shows that gold nanoparticles are uniformly distributed on the carbon substrate; C is a high-resolution transmission electron microscope image, which shows that the size of the gold nanoparticles is about 6 nm and the lattice spacing of the gold nanoparticles is 0.235 nm, which corresponds to the (111) crystal plane of the gold nanoparticles.

[0058] X-ray diffraction tests were performed on the AuNPs / NPC and NPC prepared in steps two and three, respectively, and the results are as follows: Figure 6 As shown in the figure, the peaks at 38.2°, 44.4°, 64.6° and 77.7° in AuNPs / NPC correspond to the diffraction peaks of the (111), (200), (220) and (311) planes of AuNPs, respectively. The X-ray diffraction pattern of NPC shows that the broad peaks at 24.5° and 44° correspond to the diffraction peaks of the (002) and (101) planes of carbon, respectively.

[0059] In some embodiments of the present invention, the concentration of the noble metal HAuCl4 in step three is increased or decreased, for example, it can be 12 mM or 3 mM. The CV plots of the catalytic response of AuNPs / NPCs prepared with 3 mM, 6 mM and 12 mM to H2O2 are shown below. Figure 7 As shown, the AuNPs / NPC exhibits the highest catalytic response to H2O2 when the concentration of HAuCl4 is 6 mM.

[0060] Example 2: Peroxidase Activity Analysis of AuNPs / NPCs

[0061] The peroxidase activity of AuNPs / NPC was analyzed by oxidizing different chromogenic substrates, including 3,3',5,5'-tetramethylbenzidine (TMB), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and o-phenylenediamine (OPD). The analytical process is detailed below using the oxidation of TMB by AuNPs / NPC as an example. The specific test steps are as follows:

[0062] S1: Dissolve a certain amount of H2O2 and TMB in 2.0 mL of 0.1 M acetic acid buffer solution with pH 4.0, so that the final concentrations of H2O2 and TMB are 5 mM and 0.5 mM, respectively.

[0063] S2: Then, 20 μL of AuNPs / NPC with a concentration of 1.0 mg / mL was added to the above-mentioned acetate buffer solution containing H2O2 and TMB, and incubated at 50 °C for 20 min. The absorbance of AuNPs / NPC was then measured.

[0064] Control group experiment: NPCs were used instead of AuNPs / NPCs, and the absorbance values ​​of NPCs were recorded according to the test steps of S1 and S2.

[0065] The peroxidase activity under different conditions was analyzed using the method described above, and the results are as follows: Figure 8 As shown in the figure, Figure a is a comparison of the enzyme activities of different materials, where A: AuNPs / NPC+H2O2+TMB, B: NPC+H2O2+TMB, C: AuNPs / NPC+TMB, and D: TMB+H2O2. It can be seen from the figure that NPC has the ability to catalyze the color change of TMB in the presence of H2O2. However, when AuNPs are modified, the catalytic ability of AuNPs / NPC is further enhanced, manifested as a deeper blue color accompanied by an increase in absorbance. Figure b is a comparison of the color-changing abilities of AuNPs / NPC in catalyzing ABTS (A), OPD (B), and TMB (C). It can be observed that under H2O2, AuNPs / NPC can catalyze different color-changing substrates to produce color changes, further demonstrating that AuNPs / NPC has peroxidase activity.

[0066] Example 3: Electrode based on AuNPs / NPC modification for electrochemical analysis of H2O2

[0067] Preparation of AuNPs / NPC / GCE: Before modification, the glassy carbon electrode (GCE) was polished to a mirror finish using 0.3 μm and 0.05 μm aluminum oxide. The GCE was then sonicated for 1 min in a 1:1 solution of nitric acid and water. After removing the modified electrode, the acid solution on the electrode surface was rinsed off with deionized water. Subsequently, the electrode was sonicated for 1 min each in anhydrous ethanol and deionized water. The sonicated GCE was dried with nitrogen gas. 10 μL of 1 mg / mL AuNPs / NPC was added to the electrode surface, and the electrode was dried under an infrared lamp to obtain AuNPs / NPC / GCE.

[0068] Control group: AuNPs / NPC was replaced with NPC, and the remaining steps were the same as the preparation process of AuNPs / NPC / GCE to obtain NPC / GCE.

[0069] A three-electrode system was employed, using a bare GCE or a material-modified GCE as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum electrode as the counter electrode. A CHI660E electrochemical workstation (Shanghai Chenhua) was used as the testing platform. A 0.1M phosphate buffer solution with a pH of 7.4 was prepared using potassium dihydrogen phosphate and disodium hydrogen phosphate. 6 mL of this buffer solution was placed in a 10 mL beaker as the test solution. Before electrochemical testing, the test solution was purged with high-purity nitrogen for half an hour to remove dissolved oxygen. During H₂O₂ testing, a high-purity nitrogen atmosphere was maintained throughout the process.

[0070] Cyclic voltammetry (CV) was used to verify the reduction reaction of H2O2 on the modified electrode. The CV potential window range was -1.0V to 0.8V, the scan rate was 50mV / s, the H2O2 concentration was 5mM, and the CV results for bare GCE, NPC / GCE, and AuNPs / NPC / GCE catalyzing 5mM H2O2 are as follows. Figure 9 As shown in the figure, the current response of NPC / GCE to hydrogen peroxide shows a slow decreasing slope and a small current value, while the current response of AuNPs / NPC / GCE to hydrogen peroxide shows a clear reduction peak and a large current value.

[0071] This shows that both NPC / GCE and AuNPs / NPC / GCE produce significant current responses to H2O2, with AuNPs / NPC / GCE exhibiting a stronger current response to H2O2, while bare GCE basically does not produce a current response to H2O2.

[0072] Example 4: Determination of the linear range of AuNPs / NPC / GCE for hydrogen peroxide determination

[0073] The linear range of H2O2 was determined using the amperometric it curve method (it). A 6 mL solution of 0.1 M phosphate buffer (pH 7.4) was used as the test substrate. Before testing, the substrate was purged with high-purity nitrogen for half an hour to remove dissolved oxygen. The test was conducted in a high-purity nitrogen atmosphere. The test potential was -0.4 V. The solution was continuously stirred throughout the test. After the current stabilized and stopped increasing over time, a small concentration of H2O2 was added. After the current stabilized for 100 seconds following the addition of H2O2, a slightly larger concentration of H2O2 was added. The amperometric it curve (a) and linear relationship graph (b) for H2O2 detection are shown below. Figure 10 As shown, AuNPs / NPC / GCE responds quickly to hydrogen peroxide and exhibits good linearity in the concentration ranges of 0.2-1000 μM and 1000-7000 μM.

[0074] Example 5: Stability Testing of AuNPs / NPC / GCE

[0075] The time stability and operational stability of the AuNPs / NPC / GCE prepared in Example 3 were studied using the it method.

[0076] The time stability test procedure is as follows: 6 mL of a 0.1 M phosphate buffer solution (pH 4.0) was used as the test substrate. Before the test, the substrate was purged with high-purity nitrogen for half an hour to remove dissolved oxygen. The test was conducted in a high-purity nitrogen atmosphere, with the prepared AuNPs / NPC / GCE placed in the atmosphere and stirred continuously. When the current stabilized and stopped increasing over time, 100 μM H2O2 was added. The test was stopped after 100 seconds. The AuNPs / NPC / GCE was stored in a refrigerator at 4°C, and the tests were performed on days 4, 7, 10, 13, and 16 using the same method. The it current response values ​​of 100 μM H2O2 at different days were recorded. The change in the current response of AuNPs / NPC / GCE to 100 μM after 16 days is shown below. Figure 11 As shown in Figure a, it can be seen that the current response after 16 days is 89.4% of the initial current response, indicating that the modified electrode has good stability.

[0077] The operational stability test procedure is as follows: 6 mL of a 0.1 M phosphate buffer solution with pH 7.4 was used as the test substrate. Before the test, the substrate was purged with high-purity nitrogen for half an hour to remove dissolved oxygen. The test was conducted in a high-purity nitrogen atmosphere. The prepared AuNPs / NPC / GCE was placed in the atmosphere and the test was carried out with continuous stirring. When the current stabilized and stopped increasing over time, 100 μM H2O2 was added. After 100 s, another 100 μM H2O2 was added, and the test was continued for 3000 s. After 3000 s, another 100 μM H2O2 was added, and the test was stopped after another 100 s. The current response of AuNPs / NPC / GCE to the addition of 100 μM H2O2 under continuous stirring at -0.4 V and the current response to the addition of 100 μM H2O2 after 3000 s are shown below. Figure 11 As shown in Figure b, it can be seen that after 3000s of operation, the current drops to 89.0% of the original current, indicating that the AuNPs / NPC / GCE electrode has good operational stability.

[0078] Example 6: Selectivity Testing of AuNPs / NPC / GCE

[0079] The selectivity of H2O2 was determined by the amperometric method (it). The test solution consisted of 6 mL of a 0.1 M phosphate buffer solution at pH 7.4. Before the test, the test solution was purged with high-purity nitrogen for half an hour to remove dissolved oxygen. The test was conducted in a high-purity nitrogen atmosphere. The it potential was -0.4 V. The solution was continuously stirred throughout the test. Once the current stabilized and stopped increasing over time, 100 μM hydrogen peroxide was added. Subsequently, every 90 seconds, 10 mM sodium chloride (NaCl), 10 mM potassium chloride (KCl), 10 mM calcium chloride (CaCl2), 300 μM L-tyrosine (LT), 300 μM L-proline (LP), 300 μM glucose (Glu), 300 μM dopamine (DA), 300 μM uric acid (UA), and 300 μM ascorbic acid (AA) were added sequentially. The test results are as follows: Figure 12 As shown in the figure, the above substances have little effect on the current response of H2O2, indicating that AuNPs / NPC / GCE has good anti-interference ability against H2O2.

[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing noble metal nanoparticle / carbon-based nanoszyme, characterized in that, The preparation method comprises the following steps: Melamine and cyanuric acid are respectively dissolved in dimethyl sulfoxide, and then the obtained solutions are mixed to prepare melamine-cyanuric acid supramolecular aggregates; the dissolution ratio of melamine and dimethyl sulfoxide is 1 g: 40 mL; the dissolution ratio of cyanuric acid and dimethyl sulfoxide is 2.04 g: 40 mL; Glucose and the melamine-cyanuric acid supramolecular aggregates are ground in a mass ratio of 0.25 g: 2.0 g to obtain a uniform mixture, and then the mixture is heated to 700 DEG C at a heating rate of 2.5 DEG C / min in a high-temperature pure nitrogen atmosphere, and is kept at 700 DEG C for 2 h, and then is naturally cooled to room temperature to prepare nitrogen-doped porous carbon; HAuCl4 is added to a dispersion of the nitrogen-doped porous carbon, and NaBH4 solution is added dropwise to prepare noble metal nanoparticle / carbon-based nanoszyme; the feeding ratio of the nitrogen-doped porous carbon and HAuCl4 is 10 mg: 5 mL, wherein the concentration of the HAuCl4 is 3-12 mM / 5 mL.

2. The preparation method of the noble metal nanoparticle / carbon-based nanoszyme according to claim 1, characterized in that, the step of respectively dissolving melamine and cyanuric acid in dimethyl sulfoxide, and then mixing the obtained solutions to prepare melamine-cyanuric acid supramolecular aggregates comprises the following steps: melamine is dissolved in dimethyl sulfoxide, and ultrasonic treatment is performed to obtain a colorless, clear and transparent solution A; cyanuric acid is dissolved in dimethyl sulfoxide, and ultrasonic treatment is performed to obtain a colorless, clear and transparent solution B; under stirring, the solution B is poured into the solution A to form white precipitates, and the formed white precipitates are subjected to suction filtration through an organic solvent microporous filter membrane; the white suction filtration product is placed in a vacuum drying oven and vacuum dried at 50-80 DEG C to obtain melamine-cyanuric acid supramolecular aggregates.

3. The preparation method of the noble metal nanoparticle / carbon-based nanoszyme according to claim 1, characterized in that, the step of adding HAuCl4 to a dispersion of the nitrogen-doped porous carbon, and adding NaBH4 solution dropwise to prepare noble metal nanoparticle / carbon-based nanoszyme comprises the following steps: the nitrogen-doped porous carbon is dispersed in deionized water to obtain a dispersion; HAuCl4 is added to the dispersion to obtain a nitrogen-doped porous carbon dispersion containing HAuCl4 after stirring; NaBH4 solution is added dropwise to the nitrogen-doped porous carbon dispersion containing HAuCl4, and the product is subjected to centrifugation after stirring, and is washed with deionized water; the washed product is dried to obtain noble metal nanoparticle / carbon-based nanoszyme.

4. The preparation method of the noble metal nanoparticle / carbon-based nanoszyme according to claim 1 or 3, characterized in that, the mixing ratio of the nitrogen-doped porous carbon and deionized water is 1-2 mg: 1 mL.

5. A noble metal nanoparticle / carbon-based nanoszyme, characterized in that, The preparation method is prepared by using any one of claims 1-4; the noble metal nanoparticle / carbon-based nanoszyme comprises HAuCl4 nanoparticles and nitrogen-doped porous carbon.

6. A noble metal nanoparticle / carbon-based nanoszyme modified electrode, characterized in that, The electrode comprises the noble metal nanoparticle / carbon-based nanoscale enzyme prepared by the preparation method of any one of claims 1-4 and the electrode.

7. Use of noble metal nanoparticle / carbon-based nanoszyme in biological detection, characterized in that, The noble metal nanoparticle / carbon-based nanoscale enzyme is prepared by the method of any one of claims 1-4, and the biological detection comprises detection of the content of hydrogen peroxide in the organism.

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