Copper single-atom carbon dot nanoszyme with sodase activity, preparation method and application thereof

Abstract

This invention relates to copper single-atom carbon dot nanozymes with SOD enzyme activity, their preparation methods, and applications. The copper single-atom carbon dot nanozyme with SOD enzyme activity is obtained by loading copper single atoms onto the surface of nitrogen-doped carbon quantum dots, wherein the copper single atoms are in Cu... 2+ The nitrogen-doped carbon quantum dots are dispersed on the surface of nitrogen-doped carbon quantum dots. In this invention, the surface of the nitrogen-doped carbon quantum dots contains various asymmetric C and N sites, and the presence of N is beneficial for promoting Cu... 2+ Dispersion, reduction of Cu 2+ Reunion, through N and Cu 2+ Coordination to achieve stable Cu 2+ The atomic-level dispersion ensures the high activity, stability, and metal economy of the copper single-atom carbon nanodot nanozyme with SOD enzyme activity of the present invention.

Description

Technical Field

[0001] This invention belongs to the field of nanozyme preparation technology, specifically relating to copper single-atom carbon dot nanozymes with SOD enzyme activity, their preparation methods, and applications. Background Technology

[0002] Oxidative stress damage induced by the overexpression of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in vivo is considered a major cause of many biological diseases. Natural enzymes play a crucial role in maintaining redox balance and alleviating oxidative stress damage; however, the preparation and purification of natural enzymes are complex, costly, and require stringent storage conditions. Although natural superoxide dismutase (SOD) enzymes show great promise in disease treatment, their instability under non-physiological conditions and susceptibility to proteolytic enzymes limit their practical application. Furthermore, natural SOD enzymes typically have difficulty crossing cell membranes to remove excess ROS. As a new generation of artificial enzyme mimics, nanozymes possess unique enzyme-mimicking properties and can be used for human health and disease treatment. Antioxidant nanozymes that scavenge ROS are potential materials for treating ROS-induced inflammatory damage in vivo.

[0003] Carbon quantum dots (CDs) possess various functional groups on their surface, including carbonyl, hydroxyl, and carboxyl groups, enabling the realization of diverse enzyme activities based on different enzyme catalytic active sites on their surface. Inspired by the concept of single-atom catalysts, atomically dispersed metal atoms anchored on a support provide the highest atomic utilization, thus offering more efficient active sites for biochemical reactions. Therefore, single-atom nanozymes can be constructed by mimicking the metal coordination structure of natural metalloenzymes, enabling the utilization of these metal atoms to consume superoxide radicals (O2) in cells. ·- This makes it possible. Although some single-atom nanozymes have been successfully developed, the common synthetic method of one-pot pyrolysis of metal salts, carbon and nitrogen precursors embeds some metal atoms inside the carbon skeleton, reducing the proportion of catalytic sites on the nanozyme surface and thus reducing the utilization rate of metal atoms.

[0004] The invention patent with publication number CN118146794A discloses a single-atom copper-doped near-infrared carbon dot, its preparation method and application. The single-atom copper-doped near-infrared carbon dot is obtained by hydrothermal reaction using ethylenediaminetetraacetic acid as the carbon source, copper salt as the copper source, and water as the solvent. However, the copper element in the single-atom copper-doped near-infrared carbon dot cannot be completely loaded onto the carbon dot in the form of copper single atoms. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing copper single-atom carbon dot nanozymes with SOD enzyme activity to solve the technical problem that the copper element in copper-doped carbon dot nanozymes cannot be completely loaded onto the carbon dots in the form of copper single atoms.

[0006] The second objective of this invention is to provide a copper single-atom carbon dot nanozyme with SOD enzyme activity.

[0007] The third objective of this invention is to provide an application of copper single-atom carbon dot nanozymes with SOD enzyme activity.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] Copper single-atom carbon dot nanozymes with SOD enzyme activity were obtained by loading copper single atoms onto the surface of nitrogen-doped carbon quantum dots, wherein the copper single atoms are Cu 2+ The particles are dispersed in the form of nitrogen-doped carbon quantum dots on the surface.

[0010] Furthermore, the loading of copper single atoms accounts for 5 to 20 wt% of the nitrogen-doped carbon quantum dots.

[0011] A method for preparing copper single-atom carbon dot nanozymes with SOD enzyme activity is characterized by comprising the following steps: mixing nitrogen-doped carbon quantum dot aqueous solution with a copper source and drying to obtain powder, heating the powder with microwave and purifying it to obtain the final product.

[0012] Furthermore, the preparation method of the nitrogen-doped carbon quantum dot aqueous solution is as follows: citric acid is dissolved in water, and then mixed with ethylenediamine to obtain a mixed solution. The mixed solution undergoes a hydrothermal reaction, and after centrifugation, a supernatant is obtained. The supernatant is freeze-dried to obtain nitrogen-doped carbon quantum dot powder, which is then dissolved in water to obtain the final product.

[0013] Furthermore, the microwave heating power is 600-800W; the microwave heating time is 0.5-2min.

[0014] Furthermore, the concentration of the nitrogen-doped carbon quantum dot aqueous solution is 1–5 mg / mL.

[0015] Furthermore, the hydrothermal reaction temperature is 180–200°C, and the hydrothermal reaction time is 4–6 hours.

[0016] Furthermore, for every 1.05g of citric acid, 10-15mL of water is added, and for every 1.05g of citric acid, 0.335-0.67mL of ethylenediamine is added.

[0017] Furthermore, the copper source is copper chloride; the drying method is freeze drying; and the purification method is to dissolve the microwave-heated powder in water and then perform dialysis purification.

[0018] Application of copper single-atom carbon nanodot nanozymes with SOD enzyme activity in scavenging superoxide radicals.

[0019] The beneficial effects of this invention are:

[0020] In the copper single-atom carbon dot nanozyme with SOD enzyme activity of the present invention, the copper single atoms are in the form of Cu 2+ The copper element is uniformly loaded on the surface of nitrogen-doped carbon quantum dots. The copper element on the surface of nitrogen-doped carbon quantum dots exists in the form of copper single atoms and does not contain elemental copper or copper nanoparticles.

[0021] In this invention, nitrogen-doped carbon quantum dots have various asymmetric C and N sites on their surface, and the presence of N is beneficial for promoting Cu... 2+ Dispersion, reduction of Cu 2+ Reunion, through N and Cu 2+ Coordination to achieve stable Cu 2+ The atomic-level dispersion ensures the high activity, stability, and metal economy of the copper single-atom carbon nanodot nanozyme with SOD enzyme activity of the present invention.

[0022] This invention achieves uniform loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots through short-time microwave processing. Leveraging the small size, high dispersibility, and low biotoxicity of carbon quantum dots, highly active copper single atoms with high atomic utilization are loaded onto the surface of nitrogen-doped carbon quantum dots to achieve O2 control. ·- Highly efficient removal.

[0023] The copper single-atom carbon dot nanozyme of the present invention, possessing SOD enzyme activity, has its catalytic active sites uniformly exposed on the surface of nitrogen-doped carbon quantum dots. This allows the copper single atoms to contact the substrate and further mediate the catalytic reaction. Electron spin resonance spectroscopy (ESR) testing confirmed that the activity mechanism of the copper single-atom carbon dot nanozyme with SOD enzyme activity is consistent with that of natural Cu,Zn-SOD enzymes, and that copper single atoms can be used to achieve SOD activity. ·- Perform the cleanup. Attached Figure Description

[0024] Figure 1 This is a synthetic route diagram of the copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 1.

[0025] Figure 2 The images shown are transmission electron microscope (TEM) images, average particle size curves, and optical images of the copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity in Example 4, where a is a TEM image and b is an optical image of the average particle size curve and dispersion in water.

[0026] Figure 3 Characterization diagrams of copper single-atom carbon dot nanozymes with SOD enzyme activity are shown below. a) is the XRD pattern of copper single-atom carbon dot nanozymes with SOD enzyme activity from Examples 1-4; b) is the UV-Vis absorption spectrum of copper single-atom carbon dot nanozymes with SOD enzyme activity from Examples 1-4; c) is the PL spectrum of copper single-atom carbon dot nanozymes with SOD enzyme activity from Examples 1-4; d) is the fine XPS pattern of C1s of copper single-atom carbon dot nanozymes with SOD enzyme activity from Example 4; e) is the fine XPS pattern of N1s of copper single-atom carbon dot nanozymes with SOD enzyme activity from Example 4; and f) is the Cu content of copper single-atom carbon dot nanozymes with SOD enzyme activity from Example 4. The XPS fine spectrum of 2p, g is the ESR spectrum of the copper single-atom carbon nanodot nanozyme with SOD enzyme activity in Example 4, h is the XANES spectrum of the copper single-atom carbon nanodot nanozyme with SOD enzyme activity in Example 4, and i is the Fourier transform of the CuK edge EXAFS spectrum of the copper single-atom carbon nanodot nanozyme with SOD enzyme activity, copper oxide (CuO), copper phthalocyanine (CuPc), and copper foil (Cu foll) in Example 4.

[0027] Figure 4 Copper single-atom carbon nanodot nanozymes with SOD enzyme activity for O2 ·- The scavenging performance, where a is the copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity in Examples 1-4 at a concentration of 20 μg / mL for O2. ·- The scavenging spectrum, b represents the scavenging of O2 by copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity in Example 4 at a concentration of 80 μg / mL. ·- The scavenging spectrum, c represents the O2 scavenging effect of the copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity in Example 4. ·- The cytotoxicity test data graph shows that d represents the copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity and O2 in Example 4. ·- Free radical test spectra before and after the reaction, e represents the copper single-atom carbon nanoparticle nanozyme with SOD enzyme activity and O2 in Example 4. ·- Cu before and after the reaction 2+ Paramagnetic signal spectrum. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0029] Example 1

[0030] The preparation method of copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 1 includes the following steps:

[0031] S1: Dissolve 1.05g of citric acid in 10mL of deionized water, then mix with 0.335mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with Teflon and react at 200℃ for 5h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0032] S2: 0.5 mg of solid copper chloride was magnetically stirred and mixed with 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was then microwaved in an 800 W microwave oven for 1 min. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 hours to obtain copper single-atom carbon dot (CuSAs-CDs) nanozyme with SOD enzyme activity. In Example 1, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the SOD enzyme nanozyme was 5 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 1 mg / mL.

[0033] Example 2

[0034] The preparation method of copper single-atom carbon dot nanozymes with SOD enzyme activity in Example 2 includes the following steps:

[0035] S1: Dissolve 1.05g of citric acid in 10mL of deionized water, then mix with 0.335mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with Teflon and react at 200℃ for 5h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0036] S2: 1 mg of solid copper chloride was mixed with 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution by magnetic stirring for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was then microwaved in an 800 W microwave oven for 1 minute. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 hours to obtain copper single-atom carbon dot nanozymes with SOD enzyme activity. In Example 2, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the copper single-atom carbon dot nanozyme with SOD enzyme activity was 10 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 1 mg / mL.

[0037] Example 3

[0038] The preparation method of copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 3 includes the following steps:

[0039] S1: Dissolve 1.05g of citric acid in 10mL of deionized water, then mix with 0.335mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with Teflon and react at 200℃ for 5h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0040] S2: 1.5 mg of solid copper chloride and 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution were magnetically stirred for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was microwaved in an 800 W microwave oven for 1 min. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 h to obtain copper single-atom carbon dot nanozymes with SOD enzyme activity. In Example 3, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the SOD enzyme nanozyme was 15 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 1 mg / mL.

[0041] Example 4

[0042] The preparation method of the copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 4 includes the following steps:

[0043] S1: Dissolve 1.05g of citric acid in 10mL of deionized water, then mix with 0.335mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with Teflon and react at 200℃ for 5h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0044] S2: 2 mg of solid copper chloride was mixed with 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution by magnetic stirring for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was then microwaved in an 800 W microwave oven for 1 minute. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 hours to obtain copper single-atom carbon dot nanozymes with SOD enzyme activity. In Example 4, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the SOD enzyme nanozyme was 20 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 1 mg / mL.

[0045] Example 5

[0046] The preparation method of the copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 5 includes the following steps:

[0047] S1: Dissolve 1.05g of citric acid in 13mL of deionized water, then mix with 0.5mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with Teflon and react at 180℃ for 6h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0048] S2: 2 mg of solid copper chloride was mixed with 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution by magnetic stirring for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was then microwaved in a 600 W microwave oven for 2 minutes. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 hours to obtain copper single-atom carbon dot nanozymes with SOD enzyme activity. In Example 5, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the copper single-atom carbon dot nanozyme with SOD enzyme activity was 6.7 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 3 mg / mL.

[0049] Example 6

[0050] The preparation method of the copper single-atom carbon dot nanozyme with SOD enzyme activity in Example 6 includes the following steps:

[0051] S1: Dissolve 1.05g of citric acid in 15mL of deionized water, then mix with 0.67mL of ethylenediamine. Stir magnetically for 30min to obtain a mixed solution. Transfer the mixed solution to a Teflon-lined stainless steel autoclave and react at 190℃ for 6h to obtain a brownish-black solution. Centrifuge the brownish-black solution at 12000rpm / min for 10min to remove large particles and obtain a supernatant. Freeze-dry the supernatant to obtain nitrogen-doped carbon quantum dot powder. Dissolve the nitrogen-doped carbon quantum dot powder in water to obtain a nitrogen-doped carbon quantum dot aqueous solution.

[0052] S2: 2.5 mg of solid copper chloride and 4.7 mL of nitrogen-doped carbon quantum dot aqueous solution were magnetically stirred for 2 hours until homogeneous. The mixture was then freeze-dried to obtain a powder. The powder was microwaved in a 700 W microwave oven for 0.5 min. After microwave treatment, the powder was dissolved in water and transferred to a 500 Da dialysis bag for dialyzing for 24 h to obtain copper single-atom carbon dot nanozymes with SOD enzyme activity. In Example 6, the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots in the copper single-atom carbon dot nanozyme with SOD enzyme activity was 5 wt%. The concentration of the nitrogen-doped carbon quantum dot aqueous solution was 5 mg / mL.

[0053] from Figure 2 a and Figure 2 As can be seen from b, the average size of the copper single-atom carbon dot nanozymes with SOD enzyme activity is between 4 and 5 nm. From Figure 3 As can be seen from a, with the increase of copper loading, the XRD pattern did not show the characteristic diffraction peaks of elemental copper. Figure 3 As can be seen from b, with the increase of copper loading, the characteristic absorption peaks of copper nanoparticles did not appear in the UV-Vis absorption spectrum. Figure 3 a and Figure 3 As can be seen from b, copper is not loaded onto the surface of nitrogen-doped carbon quantum dots in the form of elemental or nanoparticles, but rather in the form of single copper atoms. From Figure 3 As shown in Figure c, the fluorescence intensity of the copper single-atom carbon dot nanozyme with SOD enzyme activity decreases with increasing copper single-atom loading, indicating that copper single atoms have been loaded onto the surface of nitrogen-doped carbon quantum dots. Figure 3 f- Figure 3 As can be seen, copper single atoms are represented by Cu. 2+ The Cu quantum dots are dispersed and loaded on the surface of copper quantum dots, and Cu 2+ It coordinates with nitrogen.

[0054] The superoxide dismutase-like activity of the copper single-atom carbon nanoparticle nanozymes with SOD enzyme activity in Examples 1-4 was evaluated using the nitroblue tetrazolium (NBT) method at the same concentration. The results are as follows: Figure 4 As shown in a and 4b, with the increase of copper single-atom loading, the superoxide dismutase-like activity of the copper single-atom carbon dot nanozymes with SOD enzyme activity gradually increases. The copper single-atom carbon dot nanozymes with SOD enzyme activity in Examples 1-4 exhibited increased activity against O2 at a concentration of 20 μg / mL. ·- The scavenging rates are shown in Table 1; the copper single-atom carbon nanoparticle nanozymes with SOD enzyme activity in Examples 1-4 showed good scavenging rates against O2 at a concentration of 50 μg / mL. ·- The clearance rates are shown in Table 2. From... Figure 4 c shows that even when the concentration of copper single-atom carbon nanoparticle nanozymes with SOD enzyme activity is increased to 80 μg / mL, they still exhibit low toxicity to L929 cells. From Figure 4 As can be seen from d and 4e, copper single-atom carbon dot nanozymes O2 with SOD enzyme activity ·- The reaction can effectively remove O2. ·- Cu on the surface of copper single-atom carbon dot nanozymes with SOD enzyme activity 2+ The paramagnetic signal decreased significantly, indicating that O2 removal... ·- During the process, copper single-atom carbon nanodot nanozymes with SOD enzyme activity use copper single atoms on their surface as active centers to achieve O2. ·- The removal. Figure 4 Blank in b is used for ESR detection of O2. ·- In the O2 removal experiment, without the addition of copper single-atom carbon nanoparticles with SOD enzyme activity, ·- The addition product with the trapping agent BMPO (BMPO-O2) ·- (Corresponds to ESR signal) Figure 4 Blank in d is for ESR detection of O2. ·- In the O2 removal experiment, without the addition of copper single-atom carbon nanoparticles with SOD enzyme activity, ·- The addition product with the trapping agent BMPO (BMPO-O2) ·- (Corresponds to ESR signal) Figure 4 Blank in e is a copper single-atom carbon nanodot nanozyme with SOD enzyme activity and O2. ·- Before the reaction, the ESR signal of copper ions in copper single-atom carbon nanodot nanozymes with SOD enzyme activity was obtained by detection.

[0055] Table 1. Copper single-atom carbon nanoparticle nanozymes with SOD enzyme activity at a concentration of 20 μg / mL for O2. ·- clearance rate

[0056]

[0057] Table 2 shows the activity of copper single-atom carbon nanoparticle nanozymes with SOD enzymes at a concentration of 50 μg / mL against O2. ·- clearance rate

[0058]

[0059] As can be seen from Tables 1 and 2, the copper single-atom carbon dot nanozyme with SOD enzyme activity of the present invention has a positive effect on O2. ·- The clearance rate is much higher than that of CDs for O2. ·- The clearance rate. As the concentration of copper single-atom carbon dot nanozymes with SOD enzyme activity increases, the scavenging rate of copper single-atom carbon dot nanozymes with SOD enzyme activity against O2... ·-The removal rate also increases; when the loading of copper single atoms on the surface of nitrogen-doped carbon quantum dots increases, the removal rate of O2 by copper single-atom carbon nanodot nanozymes with SOD enzyme activity also increases. ·- The clearance rate also increases accordingly.

Claims

1. A method for preparing a copper single-atom carbon dot nanoszyme with SOD enzymatic activity, characterized in that, Obtained by loading copper single atoms onto the surface of nitrogen-doped carbon quantum dots, wherein the copper single atoms are Cu 2+ The copper single-atom nanozyme is dispersed on the surface of nitrogen-doped carbon quantum dots in the form of a copper single-atom nanoparticle; the loading of the copper single-atom nanoparticle accounts for 5-20 wt% of the nitrogen-doped carbon quantum dots; the preparation method of the copper single-atom carbon dot nanozyme with SOD enzyme activity includes the following steps: mixing an aqueous solution of nitrogen-doped carbon quantum dots with a copper source and drying it to obtain a powder, heating the powder with microwaves, and purifying it to obtain the final product; the power of the microwave heating is 600-800 W; the time of the microwave heating is 0.5-2 min.

2. The method for preparing copper single-atom carbon dot nanoszyme with SOD enzyme activity according to claim 1, characterized in that, The method for preparing the nitrogen-doped carbon quantum dot aqueous solution is as follows: citric acid is dissolved in water, and then mixed with ethylenediamine to obtain a mixed solution. The mixed solution undergoes a hydrothermal reaction, and after centrifugation, a supernatant is obtained. The supernatant is freeze-dried to obtain nitrogen-doped carbon quantum dot powder, which is then dissolved in water to obtain the final product.

3. The method for preparing copper single-atom carbon dot nanozymes with SOD enzyme activity according to claim 1, characterized in that, The concentration of the nitrogen-doped carbon quantum dot aqueous solution is 1–5 mg / mL.

4. The method for preparing copper single-atom carbon dot nanozymes with SOD enzyme activity according to claim 2, characterized in that, The hydrothermal reaction is carried out at a temperature of 180–200 °C for 4–6 h.

5. The method for preparing copper single-atom carbon dot nanoszyme with SOD enzyme activity according to claim 2, characterized in that, For every 1.05 g of citric acid, add 10 to 15 mL of water, and for every 1.05 g of citric acid, add 0.335 to 0.67 mL of ethylenediamine.

6. The method for preparing copper single-atom carbon dot nanoszyme with SOD enzyme activity according to claim 1, characterized in that, The copper source is copper chloride; the drying method is freeze drying; the purification method is to dissolve the microwave-heated powder in water and then perform dialysis purification.

7. A copper single-atom carbon dot nanoszyme with SOD enzymatic activity, characterized in that, The copper single-atom carbon dot nanozyme with SOD enzyme activity was prepared using the method described in claim 1.

8. The application of a copper single-atom carbon nanodot nanozyme with SOD enzyme activity as described in claim 7 in the scavenging of superoxide free radicals.

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