A carbon-based platinum single-atom nanozyme and its preparation method and application

Abstract

This invention belongs to the technical field of nanozyme preparation and provides a carbon-based platinum single-atom nanozyme, its preparation method, and application. The nanozyme is prepared by loading platinum single atoms or nanoclusters (Pt SAs / NCs) on the surface of a carbon-based nanomaterial. The carbon-based nanomaterial is prepared via a one-step hydrothermal method using citric acid and ethylenediamine as carbon sources. Unreacted precursors and small molecules are removed by dialysis, and then freeze-dried to yield a brownish-yellow solid powder. Then, Pt single atoms / nanoclusters are loaded onto the surface of the carbon-based nanomaterial using H2PtCl6 via sodium borohydride reduction to produce Pt SAs / NCs. Unreacted precursors and small molecules are removed by dialysis, and then freeze-dried to yield a black solid powder, the carbon-based platinum single-atom nanozyme. This nanozyme exhibits excellent peroxidase (POD)-like and glutathione oxidase (GSHOx)-like activities, producing toxic ·OH and consuming GSH, indirectly amplifying oxidative stress responses.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanozyme preparation, and specifically relates to a carbon-based platinum single-atom nanozyme and its preparation method and application. Background Art

[0002] Nanozymes are nanomaterials with enzyme-like activity. Compared to most natural enzymes, nanozymes offer advantages such as low cost, high stability, simple preparation, and the chemical and physical properties of nanomaterials. Single-atom catalysts (SACs) were first described in the early 21st century. Due to their well-defined electronic and geometric structures, these catalysts hold promise as alternatives to natural enzymes by mimicking the catalytic centers of highly evolved natural enzymes. Inspired by SACs, single-atom nanozymes (SAzymes), as a new type of nanozyme, have garnered widespread attention and have been successfully applied in cancer therapy, pollutant degradation, biocatalysis, and antimicrobial applications.

[0003] Among them, the treatment based on single-atom nanozymes is due to the fact that single-atom nanozymes can produce reactive oxygen species (ROS), such as singlet oxygen ( 1 O2), superoxide anion (O2 ·- ) and hydroxyl radicals (·OH). However, during cancer treatment, the reactive oxygen species generated are scavenged by the abundant glutathione (GSH) in the tumor microenvironment, significantly diminishing the therapeutic effect. Single-atom nanozymes have been reported to exhibit glutathione oxidase-like properties, consuming GSH and indirectly amplifying oxidative stress. In 2019, Yan et al. developed a nanozyme-based bandage using single-atom Pt / CeO2, which exhibits sustained catalytic activity. However, the ability of single Pt atoms to consume GSH has not been investigated (ACS Nano, 2019, 13, 11552−11560). Inspired by this, we believe that exploring Pt-based single-atom nanozymes with both ROS-generating and GSH-consuming enzymatic activities is of great significance. This not only provides a new strategy for the preparation of single-atom nanozymes but also expands the repertoire of Pt-based single-atom nanozymes.

[0004] Carbon-based nanomaterials possess excellent biocompatibility, low toxicity, amenable surface functionalization, and potential for light-mediated therapeutics. The abundant dangling bonds (-OH, -C=O, -NH2) and high surface area of ​​carbon-based nanomaterials facilitate the attachment and exposure of metal active sites, thereby catalyzing a variety of biochemical reactions and enhancing catalytic activity. Therefore, combining carbon-based nanomaterials with Pt atoms to construct carbon-based Pt single-atom nanozymes is a promising research area. Summary of the Invention

[0005] The purpose of the present invention is to provide a carbon-based platinum single-atom nanozyme and its preparation method and application. The carbon-based platinum single-atom nanozyme of the present invention has multiple enzyme effects, which can not only produce ·OH but also consume GSH, thereby achieving the effect of amplifying oxidative stress.

[0006] The present invention is achieved by the following technical solution: a carbon-based platinum single-atom nanozyme, which is obtained by loading platinum single atoms or nanoclusters Pt SAs / NCs on the surface of carbon-based nanomaterials.

[0007] Furthermore, the carbon-based platinum single-atom nanozyme uses citric acid and ethylenediamine as carbon sources to prepare carbon-based nanomaterials through a one-step hydrothermal method, dialyzes to remove unreacted precursors and small molecules, and freeze-dries to obtain a brown-yellow solid powder; H2PtCl6 loads Pt single atoms / nanoclusters on the surface of carbon-based nanomaterials through a sodium borohydride reduction method to produce Pt SAs / NCs, dialyzes to remove unreacted precursors and small molecules, and freeze-dries to obtain a black solid powder, which is the carbon-based platinum single-atom nanozyme.

[0008] The method for preparing the carbon-based platinum single-atom nanozyme comprises the following specific steps:

[0009] (1) Preparation of carbon-based nanomaterials: Accurately weigh 1.0507 g of citric acid, add 10 mL of ultrapure water, and sonicate to fully dissolve it. Then, add 335 μL of ethylenediamine solution to the above solution.

[0010] The solution was transferred to a polytetrafluoroethylene autoclave and placed in an oven for hydrothermal reaction at 150 °C for 5 h to obtain a brown solution;

[0011] After the reaction system temperature was naturally cooled to room temperature, the brown solution was dialyzed in a 1000 Da dialysis bag for 24 h. The solution in the dialysis bag was freeze-dried to obtain a brown solid powder;

[0012] (2) Preparation of carbon-based platinum single-atom nanozymes: Under magnetic stirring at room temperature, 5.0 mL of 37.3 mM H2PtCl6 solution was added dropwise to 5.0 mL of 1.0 mg / mL carbon-based nanomaterial solution. The pH value of the solution was adjusted to 12.0 using 0.5 M NaOH solution. Finally, an excess of NaBH4 was added dropwise until the solution changed from light brown to black.

[0013] The black solution was dialyzed in a 100 Da dialysis bag for 24 h, and the solution in the dialysis bag was freeze-dried to obtain black carbon-based platinum single-atom nanozyme solid powder.

[0014] NaBH4 uses 10 mM NaOH as solvent and the NaBH4 concentration is 10 mM.

[0015] The present invention also provides the use of the carbon-based platinum single-atom nanozyme in amplifying oxidative stress reactions.

[0016] Furthermore, the carbon-based platinum single-atom nanozyme is used as a peroxidase-like enzyme to produce ·OH. The carbon-based platinum single-atom nanozyme is used as a glutathione oxidase-like enzyme to consume GSH.

[0017] The advantages of this invention lie in the fact that the carbon-based platinum single-atom nanozyme exhibits excellent peroxidase (POD) and glutathione oxidase (GSHOx)-like activities, producing toxic ·OH and consuming GSH, indirectly amplifying oxidative stress responses. Furthermore, this is the first report of a Pt-based GSHox-like enzyme effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Transmission electron microscopy image, high-resolution transmission electron microscopy image (inset in the upper right corner), and particle size distribution diagram (inset in the lower right corner) of the carbon-based platinum single-atom nanozyme prepared in Example 1;

[0019] Figure 2 This is an elemental mapping image of the carbon-based platinum single-atom nanozyme prepared in Example 1;

[0020] Figure 3 This is a spherical aberration electron microscopy image of the carbon-based platinum single-atom nanozyme prepared in Example 1;

[0021] Figure 4 This is the thermogravimetric analysis diagram of the carbon-based platinum single-atom nanozyme prepared in Example 1;

[0022] Figure 5 The UV absorption spectra of H2PtCl6, carbon-based nanomaterials, and carbon-based platinum single-atom nanozymes in Example 1 are shown in the inset. The inset is an enlarged UV-visible absorption spectrum of the carbon-based platinum single-atom nanozyme at 500-850 nm.

[0023] Figure 6 This is the full X-ray photoelectron spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0024] Figure 7 This is the Pt4f spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0025] Figure 8 This is the N1s energy spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0026] Figure 9 This is the C1s spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0027] Figure 10This is the Cl2p spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0028] Figure 11 This is the O1s spectrum of the carbon-based platinum single-atom nanozyme in Example 1;

[0029] Figure 12 The POD effect diagram of carbon-based platinum single-atom nanozyme at different temperatures in Example 2;

[0030] Figure 13 This is the POD effect diagram of carbon-based platinum single-atom nanozyme at different reaction times in Example 2;

[0031] Figure 14 This is the POD effect diagram of carbon-based platinum single-atom nanozymes with different concentrations in Example 2;

[0032] Figure 15 This is the POD effect diagram of the carbon-based platinum single-atom nanozyme under different pH conditions in Example 2;

[0033] Figure 16 This is the POD enzyme kinetic analysis diagram of carbon-based platinum single-atom nanozyme with H2O2 as substrate in Example 2;

[0034] Figure 17 This is the POD enzyme kinetic analysis diagram of carbon-based platinum single-atom nanozyme with TMB as substrate in Example 2;

[0035] Figure 18 The fluorescence spectra of the carbon-based platinum single-atom nanozyme in Example 3 after incubation with different concentrations of GSH;

[0036] Figure 19 The fluorescence spectra of carbon-based platinum single-atom nanozymes and GSH at different reaction times in Example 3;

[0037] Figure 20 This is a graph showing the consumption of GSH by carbon-based platinum single-atom nanozymes at different concentrations in Example 3;

[0038] Figure 21 This is the kinetic analysis diagram of the GSHOx enzyme using DTNB as the substrate and carbon-based platinum single-atom nanozyme in Example 3;

[0039] Figure 22 This is the S2p spectrum after incubation of carbon-based platinum single-atom nanozyme with GSH in Example 3;

[0040] Figure 23 This is the Pt4f spectrum after incubation of carbon-based platinum single-atom nanozyme with GSH in Example 3. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the disclosure and materials cited therein are hereby incorporated by reference.

[0043] Technical equivalents to the specific embodiments described that are apparent to those skilled in the art using no more than routine experimentation are intended to be encompassed by this application.

[0044] The experimental methods in the following examples, unless otherwise specified, are all conventional methods. The instruments and equipment used in the following examples, unless otherwise specified, are all conventional laboratory instruments and equipment; the experimental materials used in the following examples, unless otherwise specified, are all purchased from conventional biochemical reagent stores.

[0045] Example 1: Preparation and structural characterization of carbon-based platinum single-atom nanozymes

[0046] Step 1: Accurately weigh 1.0507 g of citric acid and add 10 mL of ultrapure water. Dissolve thoroughly by sonication. Add 335 μL of ethylenediamine solution to the solution. Transfer the solution to a polytetrafluoroethylene autoclave and place it in an oven. React at 150°C for 5 h to obtain a brown solution.

[0047] Step 2: After the reaction system temperature is cooled to room temperature, the brown solution is dialyzed in a 1000 Da dialysis bag for 24 hours, and the solution in the dialysis bag is freeze-dried to obtain a brown-yellow carbon-based nanomaterial solid powder.

[0048] Step 3. Under magnetic stirring at room temperature, 5.0 mL of H2PtCl6 (37.3 mM) solution was added dropwise to 5.0 mL of carbon-based nanomaterial (1 mg / mL) solution. The pH value of the above solution was adjusted to 12.0 using 0.5 M NaOH solution. Finally, an excess of NaBH4 solution (10 mM, 10 mM NaOH as solvent) was added dropwise until the solution changed from light brown to black.

[0049] Step 4: The black solution is dialyzed in a 100 Da dialysis bag for 24 h, and the solution in the dialysis bag is freeze-dried to obtain a black carbon-based platinum single-atom nanozyme solid powder.

[0050] Characterization of properties Figures 1-11 :

[0051] The microscopic morphology of carbon-based platinum single-atom nanozymes is as follows: Figure 1 As shown in the TEM image, it can be seen that the carbon-based platinum single-atom nanozymes are uniformly dispersed, have a spherical structure, and the average particle size is 2.35±0.3 nm.

[0052] Figure 2 and Figure 3 The following are elemental mapping images and spherical aberration electron microscopy images of the carbon-based platinum single-atom nanozyme, respectively. It can be seen that the C, O, N, and Pt elements are evenly distributed, and Pt exists in the form of single atoms and nanoclusters. The lattice spacing is 0.12 nm and 0.15 nm, corresponding to the (311) and (220) planes of the Pt face-centered cubic (fcc) phase, respectively. The Pt content of the carbon-based platinum single-atom nanozyme was 34.8% as determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0053] Figure 4 This is the thermogravimetric analysis (TGA) result of the carbon-based platinum single-atom nanozyme. When the temperature reaches 154°C, 6.5% of the weight is lost, likely due to the loss of adsorbed water. When the temperature rises from 154°C to 778.6°C, 18.06% of the weight is lost, primarily due to the release of CO, CO₂, NO, and NO₂. Aromatic ring decomposition between 778.6°C and 900°C results in a 42.77% weight loss. At 900°C, 32.67% of the weight remains, primarily due to inorganic Pt in the carbon-based Pt single-atom nanozyme, which is consistent with the Pt content calculated by ICP-OES.

[0054] Figure 5 The UV-visible absorption spectra of H2PtCl6, carbon-based nanomaterials, and carbon-based platinum single-atom nanozymes are shown. The absorption peaks of carbon-based nanomaterials at 234 nm and 343 nm correspond to the π→π of the C=C bond, respectively. * Transition and n→π of C=O * In the UV-visible absorption spectrum of the carbon-based platinum single-atom nanozyme, the absorption peak at 335 nm is blue-shifted from the carbon-based nanomaterial's absorption peak at 343 nm. This is likely due to the Pt SAs / NCs loading on the surface of the carbon-based nanomaterial, which causes the absorption peak at 234 nm to disappear. The carbon-based platinum single-atom nanozyme has a broad absorption peak between 600 and 800 nm, indicating that the carbon-based platinum single-atom nanozyme has been successfully prepared and has photothermal conversion capabilities.

[0055] Figure 6-11 This is the XPS spectrum analysis of carbon-based platinum single-atom nanozyme. Figure 6It can be found that the carbon-based platinum single-atom nanozyme has five characteristic peaks at 530.0 eV, 399.0 eV, 283.0 eV, 196.0 eV and 70.0 eV, corresponding to O1s, N1s, C1s, Cl2p and Pt4f, respectively. The high-resolution XPS spectrum of Pt4f ( Figure 7 ) shows Pt 4+ (77.4 eV, 11.08%), Pt 2+ (76.0 and 72.5 eV, 65.52%) and Pt 0+ (73.9 eV, 23.4%) three forms of Pt. N1s spectrum ( Figure 8 ) is separated into three peaks at 401.7 eV, 400.0 eV and 399.4 eV, belonging to pyrrole N, N-C3 and CNC respectively. C1s spectrum ( Figure 9 ) has three peaks at 286.5 eV, 285.7 eV and 284.6 eV, corresponding to CO, C-OH / COC and C=C respectively. In the high-resolution Cl2p spectrum ( Figure 10 ) were observed in C-Cl (200.3 eV) and Pt-Cl (199.1 eV and 198.4 eV). High-resolution O1s spectrum ( Figure 11 ) splits into three peaks at 536.0 eV, 532.0 eV, and 531.0 eV, corresponding to NO, O=CO, and Pt(OH)2O, respectively.

[0056] Example 2: Characterization of the POD mimic enzyme effect of carbon-based platinum single-atom nanozymes:

[0057] 1. Using TMB as a peroxidase substrate, the POD activity of the carbon-based platinum single-atom nanozyme was investigated. The UV-visible absorption spectrum of the carbon-based platinum single-atom nanozyme was measured by adjusting the reaction conditions (reaction temperature, reaction time, carbon-based platinum single-atom nanozyme concentration, and pH), and the absorbance at 652 nm was recorded.

[0058] Figure 12-15 The optimal reaction conditions for the POD-like effect of carbon-based platinum single-atom nanozymes (reaction temperature, reaction time, concentration of carbon-based platinum single-atom nanozymes, and pH value) were explored. As the temperature increased from 13°C to 45°C, the POD mimic enzyme activity of carbon-based platinum single-atom nanozymes gradually increased. However, when the temperature continued to rise to 55°C, the POD mimic enzyme activity of carbon-based platinum single-atom nanozymes decreased. Figure 12 ), indicating that high temperature will inhibit the POD mimetic enzyme activity of carbon-based platinum single-atom nanozymes. As the reaction time increases, the POD mimetic enzyme activity of carbon-based platinum single-atom nanozymes gradually increases and remains basically stable after 45 minutes ( Figure 13 ).like Figure 14As shown in the figure, high concentrations of carbon-based platinum single-atom nanozymes can enhance their POD mimetic enzyme activity, but when the concentration is greater than 200 μg / mL, the enhancement effect is significantly weakened. In terms of pH value, carbon-based platinum single-atom nanozymes only exhibit POD mimetic enzyme activity in acidic environments, and the stronger the acidity, the stronger the POD mimetic enzyme activity ( Figure 15 ).

[0059] 2. Add 4.0 μL of TMB (25 mM) to 1.0 mL of carbon-based platinum single-atom nanozyme (200 μg / mL, sodium acetate buffer pH = 4) and record the change in the absorbance intensity of carbon-based platinum single-atom nanozyme at 652 nm over time under different H2O2 concentrations (0.5-40 mM).

[0060] 3. Add 20 mL of H2O2 (1.0 mM) to 1.0 mL of carbon-based platinum single-atom nanozyme (200 μg / mL, sodium acetate buffer pH = 4) and record the change in the absorbance intensity of carbon-based platinum single-atom nanozyme at 652 nm over time under different concentrations of TMB (75-265 μM).

[0061] By V=(V max ×C) / (K m +C), calculate V with H2O2 / TMB as substrate max and K m Where V is the initial reaction rate, C is the concentration of substrate (H2O2 / TMB), V max is the maximum initial velocity, K m is the Michaelis constant.

[0062] When the concentrations of TMB and H2O2 were fixed at 100 μM and 20 μM, respectively, different concentrations of H2O2 (0.5-40 mM, Figure 16 ) and TMB (75-265 μM, Figure 17 ) can obtain different Michaelis-Menten curves. The maximum reaction rate of H2O2 and TMB (V max ) and the Michaelis-Menten constant (K m ) were 3.27×10 -8 M / s and 4.02 mM and 12.20×10 -8 M / s and 0.33 mM.

[0063] The reaction temperature was controlled at 45°C, the reaction time was 45 minutes, the concentration of carbon-based platinum single-atom nanozyme was 200 μg / mL, and the acidic conditions were maintained. When the concentrations of TMB and H2O2 were fixed at 100 μM and 20 μM, respectively, the maximum reaction rate (V max) and the Michaelis-Menten constant (K m ) were 3.27×10 -8 M / s and 4.02 mM and 12.20×10 -8 M / s and 0.33mM.

[0064] Example 3: Characterization of GSHOx mimetic enzymes of carbon-based platinum single-atom nanozymes:

[0065] 1. Different concentrations of GSH (0.0-1.0 mM) were added to carbon-based platinum single-atom nanozymes (0.9 mg / mL). After incubation at 37°C for 1 h, the fluorescence spectra were measured.

[0066] GSH (1.0 mM) was added to the carbon-based platinum single-atom nanozyme (0.9 mg / mL), and the fluorescence spectra of the carbon-based platinum single-atom nanozyme were measured after incubation at 37°C for different times.

[0067] like Figure 18 As shown in the figure, as the concentration of GSH increases from 0.0 mM to 1.0 mM, the fluorescence intensity of the carbon-based platinum single-atom nanozyme gradually increases. GSH (1.0 mM) was added to the carbon-based platinum single-atom nanozyme (0.9 mg / mL) and incubated at 37°C for different times, and the fluorescence intensity was tested. Figure 19 The results showed that the fluorescence intensity of the carbon-based platinum single-atom nanozyme gradually increased with the increase of incubation time. GSH (1.0 mM) was added to carbon-based platinum single-atom nanozymes at different concentrations and the residual amount of GSH was measured after incubation at 37°C for 1 hour.

[0068] 2. Add different concentrations of carbon-based platinum single-atom nanozymes (0.0-600 μg / mL) to 1.0 mM GSH solution. After incubation at 37°C for 1 h, add 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB, 200 μg / mL), measure the UV-visible absorption spectrum, and record the absorbance at 412 nm.

[0069] DTNB (1.6 mg / mL) was added to the carbon-based platinum single-atom nanozyme (0.9 mg / mL), and the concentration of GSH was adjusted (0.6-1.6 mM). The formula: V = (V max ×C) / (K m +C), calculate K m and V max .

[0070] Depend on Figure 20 It can be seen that as the concentration of carbon-based platinum single-atom nanozymes increases, the residual amount of GSH becomes less and less. This shows that carbon-based platinum single-atom nanozymes can consume GSH through the effect of glutathione oxidase. Figure 21 As shown, K m and V max The calculated results were 1.04 mM and 7.46×10 -6 M / s.

[0071] 3. GSH (1.0 mM) was added to the carbon-based platinum single-atom nanozyme (0.9 mg / mL), incubated at 37°C for 1 h, and freeze-dried to obtain a solid powder for XPS analysis.

[0072] The XPS differences of carbon-based platinum single-atom nanozymes before and after incubation with GSH were tested and compared. Figure 22 It can be seen that the carbon-based platinum single-atom nanozyme reacts with GSH to produce a disulfide bond. 0+ Content (23.4%, Figure 7 ) compared to the product of the reaction between carbon-based platinum single-atom nanozymes and GSH. 0+ The content increased to 41.24% ( Figure 23 ), indicating that GSH can convert Pt 2+ Reduction to Pt 0+ , which itself is converted into GSSG.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon-based platinum single-atom nanozyme, characterized by: The carbon-based platinum single-atom nanozyme is obtained by loading platinum single atoms or nanoclusters Pt SAs / NCs on the surface of carbon-based nanomaterials; The carbon-based platinum single-atom nanozyme uses citric acid and ethylenediamine as carbon sources, and prepares carbon-based nanomaterials through a one-step hydrothermal method. Unreacted precursor substances and small molecules are removed by dialysis, and then freeze-dried to obtain a brown-yellow solid powder. H2PtCl6 is used to load Pt single atoms / nanoclusters on the surface of carbon-based nanomaterials through a sodium borohydride reduction method to produce Pt SAs / NCs. Unreacted precursor substances and small molecules are removed by dialysis, and then freeze-dried to obtain a black solid powder, which is the carbon-based platinum single-atom nanozyme.

2. The method for preparing the carbon-based platinum single-atom nanozyme according to claim 1, characterized in that: The specific steps are as follows: (1) Preparation of carbon-based nanomaterials: Accurately weigh 1.0507 g of citric acid, add 10 mL of ultrapure water to it, and sonicate to fully dissolve it. Then, add 335 μL of ethylenediamine solution to the above solution; The solution was transferred to a polytetrafluoroethylene autoclave and placed in an oven for hydrothermal reaction at 150°C for 5 h to obtain a brown solution; After the reaction system temperature was naturally cooled to room temperature, the brown solution was dialyzed in a 1000Da dialysis bag for 24 hours, and the solution in the dialysis bag was freeze-dried to obtain a brown solid powder; (2) Preparation of carbon-based platinum single-atom nanozymes: Under magnetic stirring at room temperature, 5.0 mL of 37.3 mM H2PtCl6 solution was added dropwise to 5.0 mL of 1.0 mg / mL carbon-based nanomaterial solution. The pH value of the solution was adjusted to 12.0 using 0.5 M NaOH solution. Finally, an excess of NaBH4 was added dropwise until the solution changed from light brown to black. The black solution was dialyzed in a 100Da dialysis bag for 24 hours, and the solution in the dialysis bag was freeze-dried to obtain black carbon-based platinum single-atom nanozyme solid powder.

3. The method for preparing a carbon-based platinum single-atom nanozyme according to claim 2, characterized in that: NaBH4 was prepared using 10 mM NaOH as solvent, and the concentration of NaBH4 was 10 mM.

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