Preparation method and application of amino acid-derived carbon dot nanozyme

Abstract

The present invention provides a method for preparing and applying amino acid-derived carbon dot nanozymes, belonging to the field of new biomedical materials technology. The amino acid comprises one of histidine, proline, cysteine, tryptophan, aspartic acid, arginine, lysine, methionine, and phenylalanine; the mass ratio of the amino acid to citric acid monohydrate is 1:1 to 1:5. The amino acid-derived carbon dots proposed in the present invention have free radical scavenging activity and superoxide dismutase-like properties, exhibiting low toxicity and good biosafety at the cellular, nematode, and animal levels. Furthermore, the amino acid-derived carbon dot nanozymes exhibit excellent anti-inflammatory activity, downregulating cellular inflammation, reducing oxidative stress damage to nematodes, improving intestinal flora structure, increasing the richness and diversity of intestinal flora, and alleviating and treating DSS-induced ulcerative colitis in mice. The nanozymes can be further applied to the preparation of drugs for treating inflammatory bowel disease.

Description

Technical Field

[0001] The present invention belongs to the technical field of new biomedical materials, and specifically relates to a preparation method and application of amino acid-derived carbon dot nanozymes. Background Art

[0002] Inflammatory bowel disease (IBD) is a chronic, idiopathic inflammatory disease of the intestine. Recent clinical and experimental evidence has shown that excessive free radical production, particularly reactive oxygen species (ROS) and reactive nitrogen species (RNS), dominates and exacerbates the progression of IBD at the site of intestinal inflammation. The recent discovery of antioxidant nanozymes has brought great promise for the treatment of IBD. To effectively eliminate reactive oxygen species (ROS), various metal-based nanozymes have been developed for the treatment of IBD. Cobalt oxide nanozymes have been reported to utilize the successful strategy of scavenging ROS to inhibit DSS-induced colitis by targeting the NLRP3 inflammasome (Chen, Ziying et al. “2D Cobalt Oxyhydroxide Nanozymes Inhibit Inflammation by Targeting the NLRP3 Inflammasome.” Advanced Functional Materials (2023): 2214693.). This demonstrates the potential role of metal-based nanozymes in preventing and treating related inflammatory diseases, but their unstable elimination activity and potential digestive tract metal ion leakage seriously limit the practical application of metal nanozymes in the biomedical field.

[0003] In particular, carbon-based nanomaterials offer advantages over metal-based nanozymes, such as high chemical stability, high catalytic activity, low toxicity, and biosafety, and are expected to play a potential role in the prevention and treatment of inflammatory diseases. Carbon dots (CDs), a novel carbon-based nanomaterial with a size less than 10 nm, have been widely used in the biomedical field due to their inherent nanozyme activity, small size, good biosafety, and ease of surface modification and functionalization.

[0004] CDs can be synthesized from different precursors, such as citric acid, glucose, β-cyclodextrin, L-ascorbic acid, graphene oxide, and various biomass materials. Studies have shown that precursors are key factors affecting the activity of CDs enzymes (Gao, Wenhui et al. "Deciphering the catalytic mechanism of superoxide dismutase activity of carbon dot nanozyme." Nature Communications (2023) 14: 160). Amino acids, as the basic building blocks of proteins, play an important role in maintaining human nitrogen balance and normal physiological activities. Based on this, the present invention selects various amino acids as precursors and prepares an amino acid-derived carbon dot nanozyme by hydrothermal method for better application in the biomedical field. Summary of the Invention

[0005] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to quickly obtain a metal-free carbon dot nanozyme with stable chemical properties, high free radical scavenging efficiency, good biocompatibility, and can be applied

[0006] In the preparation of anti-inflammatory drugs.

[0007] The present invention also provides a method for preparing the above-mentioned amino acid-derived carbon dot nanozyme and its application in preparing drugs for treating inflammatory bowel disease (IBD).

[0008] In order to achieve the above objectives, the present invention uses different types of amino acids and monohydrated citric acid as precursors, and then generates carbonized products through a one-step hydrothermal / solvothermal method, and then obtains the amino acid-derived carbon dot nanozymes through separation and purification.

[0009] The above-mentioned preparation method based on different types of amino acid carbon dots specifically includes the following steps:

[0010] (1) Weighing amino acids and citric acid monohydrate, adding them to a solvent, transferring the solution into a polytetrafluoroethylene-lined reactor, heating to 160-200°C, heating for 8-24 hours, and then cooling to room temperature to obtain a yellow carbon dot solution;

[0011] (2) The yellow carbon dot solution is post-treated to obtain amino acid-derived carbon dot nanozymes. The post-treatment comprises filtering the yellow carbon dot solution with a 0.22 μm filter membrane, collecting the filtrate, dialyzing the solution with a 500-1000 molecular weight dialysis membrane for 36-72 hours, collecting the dialyzed solution, and vacuum freeze-drying to obtain a solid powder.

[0012] The amino acid in step (1) comprises one of histidine, proline, cysteine, tryptophan, aspartic acid, arginine, lysine, methionine and phenylalanine.

[0013] Preferably, the amino acid is histidine.

[0014] The amino acid and citric acid monohydrate described in step (1) are dissolved in 50-100 mL of a solvent at a mass ratio of 1 g:1 g to 1 g:5 g; wherein the solvent comprises double distilled water and / or an organic solvent; and the organic solvent comprises N,N-dimethylformamide and ethanol.

[0015] In step (2), a 0.22 μm filter membrane was used for filtration, and the filtration was repeated three times.

[0016] The dialysis solution used in step (2) is double-distilled water, which is replaced every 4 hours until the external solution becomes clear. The dialysis time can be appropriately extended or shortened depending on the sample. A solid powder is obtained after vacuum freeze-drying.

[0017] An amino acid-derived carbon dot nanozyme is prepared by the above-mentioned preparation method. The amino acid-derived carbon dot nanozyme can efficiently scavenge free radicals.

[0018] The amino acid-derived carbon dot nanozyme can be used in the preparation of anti-inflammatory drugs.

[0019] Furthermore, the amino acid-derived carbon dot nanozyme can be used in the preparation of drugs for treating inflammatory bowel disease.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The amino acid-derived carbon dot nanozymes prepared by the present invention have a small average particle size, rich oxygen- and nitrogen-containing functional groups on the surface, good water solubility, and can be widely used in the biomedical field.

[0022] (2) The amino acid-derived carbon dot nanozymes prepared by the present invention do not contain metal elements, are non-toxic, have high biosafety, and exhibit good free radical scavenging activity and certain superoxide dismutase-like activity both in vitro and in vivo, as well as good biocompatibility. Based on this, the amino acid-derived carbon dot nanozymes can be effectively used to prepare drugs for the treatment of inflammatory bowel disease (IBD).

[0023] (3) Compared with natural enzymes, the amino acid-derived carbon dot nanozymes prepared by the present invention have low preparation and purification costs, stable chemical properties, and can work efficiently in harsh environments (strong acid, strong alkali) and disease conditions, providing new ideas for the application of nanomaterials in anti-oxidative stress.

[0024] (4) The amino acid-derived carbon dot nanozymes prepared by the present invention can improve the intestinal flora structure of ulcerative colitis, increase the richness and diversity of intestinal flora, and alleviate the damage of the intestinal mucus layer in mice, and have good application prospects in the preparation of drugs for the treatment of inflammatory diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the DPPH free radical scavenging ability of each amino acid-derived carbon dot nanozyme obtained in Example 2 of the present invention;

[0026] Figure 2 Transmission electron microscopy morphology (A) and Fourier transform infrared spectrum (B) of the histidine-derived carbon dot nanozyme obtained in Example 2 of the present invention;

[0027] Figure 3 The superoxide dismutase-like activity of the histidine-derived carbon dot nanozyme obtained in Example 2 of the present invention;

[0028] Figure 4 This is a biosafety evaluation of the histidine-derived carbon dot nanozyme in Example 6 of the present invention. Figure A shows the cytotoxicity of His-CDs against mouse mononuclear macrophage RAW264.7 cells; Figure B shows the cell development of His-CDs; Figure C shows a micrograph of nematodes after one week of His-CDs feeding; Figure D shows the body length of nematodes after one week of His-CDs feeding; Figure E shows the number of nematode movements within 15 seconds after one week of His-CDs feeding; and Figure F shows an H&E-stained image of sections of major mouse organs 14 days after oral administration of His-CDs.

[0029] Figure 5 This is an evaluation of the anti-inflammatory ability of the histidine-derived carbon dot nanozymes in Example 7 of the present invention at the cellular and nematode levels. Figure A shows the effect of His-CDs intervention on the content of reactive oxygen species in M1 macrophages; Figures B and C show the effect of His-CDs on the mRNA levels of inflammatory factors TNF-α and IL-1β in M1 macrophages, respectively; Figure D shows the MDA content in nematodes in different treatment groups; and Figure E shows the mRNA level of the oxidative stress gene SOD-1 in nematodes in different treatment groups.

[0030] Figure 6 Figure 8 shows the effect of histidine-derived carbon dot nanozymes on the alleviation of DSS-induced acute colitis. Figure A shows the weight changes and total weight loss of mice from day 7 to day 21; Figure B shows the disease activity index (DAI) scores of mice in each group from day 7 to day 21; Figure C shows the colon length of mice in each group; Figure D shows representative colon photographs of mice in each group; Figures E and F show the relative expression levels of inflammatory factors IL-1β and TNF-α mRNA in the colon tissue of mice, respectively.

[0031] Figure 7 These are the photos and histopathological scores of the colon tissues of each group of mice in Example 8 of the present invention stained with hematoxylin and eosin.

[0032] Figure 8 The His-CDs in Example 9 of the present invention alleviated DSS-induced changes in the composition of the intestinal microbiota. Figure A is a Venn diagram showing overlapping operational taxonomic units in the intestinal microbiota of three groups of mice; Figures B and C are studies of alpha diversity based on the Simpson and Sobs indices, respectively.

[0033] Figure 9 is the average relative abundance of each bacterial group at the phylum level in Example 9 of the present invention.

[0034] Figure 10 is the average relative abundance of each bacterial group at the genus level in Example 9 of the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described herein by the following embodiments. It should be understood that the following embodiments are merely illustrative of the present invention and are not intended to limit the present invention. A person skilled in the art can and should be aware that any simple variation or substitution based on the essence of the present invention should fall within the scope of protection claimed by the present invention.

[0036] Example 1

[0037] The preparation of amino acid-derived carbon dot nanozymes is as follows:

[0038] (1) Histidine-derived carbon dot nanozymes (His-CDs): 1 g of histidine and 5 g of citric acid monohydrate were weighed and added to 100 mL of double-distilled water. The solution was added to a 100 mL polytetrafluoroethylene-lined reactor and heated in an oven at 160 °C for 8 h to obtain a yellow carbon dot solution.

[0039] (2) The yellow carbon dot solution was poured into a beaker and filtered through a 0.22 μm filter membrane. The solution was then dialyzed using a 500 molecular weight dialysis membrane for 36 h. The dialyzed solution was filtered through a 0.22 μm filter membrane and poured into a glass petri dish. The solution was refrigerated at -20°C and freeze-dried using a vacuum freeze dryer to obtain a solid powder.

[0040] (3) adding ultrapure water to the solid powder obtained above, dissolving it by ultrasonication, and filtering with a 0.22 μm water filter to remove the insoluble components. The obtained filtrate is the histidine-derived carbon dot nanozyme;

[0041] (4) The preparation of the remaining amino acid-derived carbon dot nanozymes was based on the synthesis and post-processing methods of His-CDs in (1) to (3). According to the names of the precursor amino acids in the present invention, they were named proline carbon dots (Pro-CDs), cysteine ​​carbon dots (Cys-CDs), tryptophan carbon dots (Trp-CDs), aspartic acid carbon dots (Asp-CDs), arginine carbon dots (Arg-CDs), lysine carbon dots (Lys-CDs), methionine carbon dots (Met-CDs) and phenylalanine carbon dots (Phe-CDs).

[0042] Example 2 In this example, amino acid-derived carbon dot nanozymes were prepared under different conditions. The specific steps are as follows:

[0043] (1) Histidine-derived carbon dot nanozymes (His-CDs): 1 g of histidine and 1 g of citric acid monohydrate were weighed and added to 50 mL of double-distilled water. The solution was added to a 100 mL polytetrafluoroethylene-lined reactor and heated in an oven at 200 °C for 12 h to obtain a yellow carbon dot solution.

[0044] (2) The yellow carbon dot solution was poured into a beaker and filtered through a 0.22 μm filter membrane. The solution was then dialyzed using a 500 molecular weight dialysis membrane for 48 h. The dialyzed solution was filtered through a 0.22 μm filter membrane and poured into a glass Petri dish. The solution was refrigerated at -20°C and freeze-dried using a vacuum freeze dryer to obtain a solid powder.

[0045] (3) adding ultrapure water to the solid powder obtained above, dissolving it by ultrasonication, and filtering with a 0.22 μm water filter to remove the insoluble components. The obtained filtrate is the histidine-derived carbon dot nanozyme;

[0046] (4) The preparation of the remaining amino acid-derived carbon dot nanozymes was based on the synthesis and post-processing methods of His-CDs in (1) to (3). According to the names of the precursor amino acids in the present invention, they were named proline carbon dots (Pro-CDs), cysteine ​​carbon dots (Cys-CDs), tryptophan carbon dots (Trp-CDs), aspartic acid carbon dots (Asp-CDs), arginine carbon dots (Arg-CDs), lysine carbon dots (Lys-CDs), methionine carbon dots (Met-CDs) and phenylalanine carbon dots (Phe-CDs).

[0047] Example 3

[0048] Amino acid-derived carbon dot nanozymes were prepared according to the method in Example 2 (1)-(4), except that the solvent in this example was N,N-dimethylformamide (DMF).

[0049] Example 4

[0050] Amino acid-derived carbon dot nanozymes were prepared according to the method in Example 2 (1)-(4), except that the solvent in this example was a mixture of DMF and double-distilled water in a volume ratio of 1:1.

[0051] Example 5

[0052] The basic physicochemical properties of the carbon dot nanozyme prepared in Example 2 were measured.

[0053] (1) DPPH free radical scavenging activity

[0054] Prepare 0.1mM DPPH ethanol solution, then mix 100μL amino acid-derived carbon dot nanozyme aqueous solution (500μg / mL) with 1mL DPPH solution, incubate in the dark for 30min, and measure the absorption curve of each solution using a UV spectrophotometer. Figure 1 This reflects the DPPH free radical scavenging ability of the amino acid-derived carbon dot nanozymes in Example 2. It can be seen that after the addition of amino acid-derived carbon dot nanozymes, the characteristic absorption peak of DPPH free radicals at 517 nm in the system is reduced, and the histidine-derived carbon dot nanozymes (His-CDs) have the best scavenging effect.

[0055] Subsequent experiments showed that the DPPH free radical scavenging ability of the amino acid-derived carbon dot nanozymes obtained in Examples 1, 3, 4 and 5 also met the requirements. Figure 1 Therefore, histidine-derived carbon dot nanozymes were selected for subsequent experiments.

[0056] (2) Characterization of morphology and surface functional groups

[0057] The morphology of histidine-derivatized carbon dot nanozymes (His-CDs) was characterized by JEM-F200 transmission electron microscopy. Fourier transform infrared (FT-IR) spectra were collected using a Bruker Hyperion 2000 spectrometer. Figure 2 Figure A shows the morphology of the histidine-derived carbon dot nanozyme. The His-CDs are evenly distributed with an average diameter of 2.5 ± 0.4 nm. As shown in the HRTEM image (inset), the lattice spacing is 0.21 nm, corresponding to the (100) crystal plane of graphite. Figure 2 Figure B is the Fourier transform infrared spectrum of His-CDs, where 3460 cm-1 is the stretching vibration peak of the hydroxyl group and 1576 cm-1 is the asymmetric stretching vibration peak of the carboxyl group C=O.

[0058] (3) Superoxide dismutase (SOD) activity assay

[0059] The SOD enzyme activity of His-CDs was determined using the Beyotime total superoxide dismutase activity detection kit (WST-8 method). Figure 3 The results reflect the superoxide dismutase (SOD) activity of His-CDs. Figure 3 As can be seen in Figure A, the SOD inhibition rate of His-CDs is 50%. Figure 3 From Figure B, we can calculate that the SOD enzyme activity of His-CDs is approximately 125 U / mg.

[0060] Example 6

[0061] Biosafety evaluation of amino acid-derived carbon dot nanozymes:

[0062] Cell level: His-CDs with a final concentration of 0-1.25 mg / mL in Example 2 were co-cultured with mouse mononuclear macrophage RAW264.7 for 24 h, and the survival rates of cells in different treatment groups were determined by CCK-8 assay. Figure 4 As shown in Figure A, when the concentration of His-CDs was as high as 0.5 mg / mL, the survival rate of RAW264.7 was still greater than 80%, showing good biocompatibility. After co-culturing RAW264.7 with His-CDs at a final concentration of 0.2 mg / mL for 1 hour, the cells were observed using a laser confocal microscope. Figure 4 As shown in B, after 1 h of co-culture, His-CDs can enter the cells and emit bright blue light under the 405 nm channel. The cells are round and in good condition.

[0063] Nematode level: Caenorhabditis elegans was used as the experimental animal to explore the effects of feeding His-CDs on the body length and movement frequency of nematodes. The experimental groups were as follows: the control group used Escherichia coli OP50 to feed the nematodes, and the experimental group used OP50 mixed with 100 μg / mL His-CDs to feed the nematodes. Use a picker to transfer the synchronized L4 nematodes to the corresponding NGM plates, at least 3 plates per group, about 200 nematodes per plate, and culture them upside down at 20°C. This was recorded as day 0. Transfer the nematodes on each culture plate to a new NGM every one or two days. On the 7th day, randomly pick at least 10 live nematodes in each group using a picker, gently place them on a water agar plate, observe them under a microscope, and measure and record the body length of the nematodes using LAZ EZ software. The experiment was repeated three times independently. The body length of the nematodes reflects the growth status and growth rate of the nematodes. Figure 4 Middle C shows microscopic photos of different groups of Caenorhabditis elegans. Figure 4 Figures D and E respectively counted the body length and movement times of nematodes in each group. The results showed that there was no significant difference in the body length and movement times of nematodes fed with mixed diet compared with those of the control group.

[0064] Animal level: After the His-CDs in Example 2 were continuously gavaged into mice for 14 days, H&E staining of the main organ sections was as follows: Figure 4 As shown in Figure F, no obvious pathological damage was observed compared with the control group, demonstrating the safety of His-CDs.

[0065] Example 7

[0066] The cell experiment was divided into three groups: the control group was composed of normally cultured RAW264.7 cells; the model group (LPS group) was composed of RAW264.7 cells induced by lipopolysaccharide to transform into M1 macrophages that can produce pro-inflammatory factors; the CDs group was based on the model group, and His-CDs prepared in Example 2 were added and co-cultured for 24 hours. The reactive oxygen species detection kit was used to determine the level of intracellular reactive oxygen species in the presence or absence of His-CDs. Figure 5 As shown in Figure A, compared with the model group, the level of intracellular reactive oxygen species was significantly reduced after His-CDs intervention. The relative expression of M1 macrophage markers (TNF-α and IL-1β) in cells was detected by real-time fluorescence quantitative PCR. Figure 5 As shown in Figures B and C, the His-CDs prepared in Example 2 can reduce the expression of M1 macrophage markers and exhibit a good anti-inflammatory effect at the cellular level.

[0067] Caenorhabditis elegans was used as the experimental animal, and an oxidative stress model was induced using 0.2 mM juglone. Synchronized L4 nematodes were cultured on NGM plates with or without His-CDs for 7 days, then harvested and assayed according to the instructions of the MDA assay kit. The amount of MDA reflects the degree of peroxidation in the body, indirectly reflecting the degree of cell damage. Figure 5 As shown in Figure D, the MDA content in the model group nematodes was significantly increased, and the MDA content after His-CDs intervention was significantly reduced compared with the model group, indicating that His-CDs intervention can effectively alleviate the damage to cells in nematodes in the oxidative stress model. Figure 5 The mRNA levels of the oxidative stress gene SOD-1 in nematodes in different treatment groups of E also proved that His-CDs intervention can promote the expression of the SOD-1 gene and regulate oxidative stress.

[0068] Example 8

[0069] The His-CDs described in Example 2 were used to treat mild acute inflammatory bowel disease in mice induced by dextran sulfate sodium salt (DSS). C57BL / 6 mice were randomly divided into a control group, a DSS model group, and a His-CDs group (DSS + CDs, 25 mg / kg). A colitis model was established in mice by drinking 2.5% (w / v) DSS for 7 consecutive days, while the control group was given an equal amount of drinking water. Following modeling, the mice were gavage-administered for 14 consecutive days. Mouse weights were recorded daily, and feces and blood in stool were observed. Colon tissue was collected from each group on day 14.

[0070] like Figure 6 As shown in Figure A, His-CDs intervention alleviated weight loss in colitis mice. After modeling, the DAI scores of both the DSS and His-CDs groups reached around 8. After 14 days of oral gavage, the DAI score of the DSS group fluctuated around 8, and oral gavage with sterile water could not reduce the DAI score. However, after 14 days of oral gavage with His-CDs, the DAI score showed a downward trend ( Figure 6 The colon length of each group of mice was measured with a ruler. The statistical results showed that the intervention of His-CDs alleviated the shortening of the colon in colitis mice ( Figure 6 Middle C). Figure 6 The representative colon photo in Figure D also proves this conclusion. Real-time fluorescence quantitative PCR was used to detect the relative expression of inflammatory factors in the colon tissue of each group of mice. The results showed that His-CDs could downregulate the pro-inflammatory factor IL-1β ( Figure 6 E), TNF-α ( Figure 6 F) mRNA expression levels. Figure 7 HE staining also revealed goblet cell loss, inflammatory cell infiltration, and mucosal damage in the colonic tissue of the model group. In contrast, the colonic tissue in the His-CDs-treated group remained nearly intact, with significantly lower histopathological scores compared to the model group. These results demonstrate that His-CDs treatment can alleviate DSS-induced colitis in mice and alleviate intestinal mucus damage.

[0071] Example 9

[0072] The His-CDs in Example 2 were administered orally to mice with DSS-induced ulcerative colitis. After 14 days, feces from each group of mice were collected to investigate changes in the intestinal microbiota of the mice. As shown in the Venn diagram, the control group, DSS group, and His-CDs group contained 114, 75, and 99 different microorganisms, respectively. The number of OTUs in the DSS group was lower than that in the control group and CDs group. This suggests that CDs intervention alleviated the DSS-induced reduction in the number of OTUs and enhanced the diversity of intestinal microorganisms in mice ( Figure 8In addition, the community diversity (Simpson index) and community richness (SOBs) of the His-CDs group were significantly higher than those of the DSS group ( Figure 8 Thus, His-CDs intervention alleviated the decrease in gut microbiota diversity and richness induced by DSS.

[0073] At the phylum level, Firmicutes and Bacteroidetes were the dominant phyla in the fecal microbiota ( Figure 9 ). Studies have shown that an increase in the ratio of Firmicutes to Bacteroidetes indicates a higher level of inflammation in the body. Compared with the DSS group, the ratio of Firmicutes to Bacteroidetes in the intestines of mice in the His-CDs group was significantly reduced. At the genus level, compared with the DSS group, the relative abundance of Bacteroidetes norank_f_Muribaculaceae in the intestines of mice in the His-CDs group was significantly increased, and the relative abundance of Allobaculum and Dubosiella were significantly increased ( Figure 10 ). norank_f_Muribaculaceae can reduce inflammation, inhibit harmful bacteria and oxidative stress, and improve intestinal mucosal inflammation. Allobaculum and Dubosiella can produce short-chain fatty acids to provide an energy source for intestinal mucosal cells, promote the proliferation of intestinal epithelial cells, maintain the intestinal barrier, and resist the occurrence of inflammation. Based on this, the amino acid-derived carbon dot nanozymes prepared by the present invention can improve the intestinal flora structure of ulcerative colitis, increase the richness and diversity of intestinal flora, alleviate the damage of the intestinal mucus layer in mice, and have good application prospects in the preparation of drugs for the treatment of inflammatory diseases.

Claims

1. Application of amino acid-derived carbon dot nanozymes in the preparation of anti-ulcerative colitis drugs, characterized in that: The amino acid-derived carbon dot nanozyme is prepared according to the following steps: (1) Weighing an amino acid and citric acid monohydrate and adding them to a solvent, transferring the resulting solution into a polytetrafluoroethylene-lined reactor, and heating the reaction to obtain a yellow carbon dot solution; the amino acid is histidine, the heating reaction temperature is 160-200 °C, and the reaction time is 8-24 h; (2) The yellow carbon dot solution is post-treated to obtain amino acid-derived carbon dot nanozymes; the post-treatment comprises filtering the yellow carbon dot solution with a 0.22 μm filter membrane and collecting the filtrate, then dialyzing the solution with a 500-1000 molecular weight dialysis membrane for 36-72 h, and vacuum freeze-drying to obtain a solid powder.

2. The use of the amino acid-derived carbon dot nanozyme according to claim 1 in the preparation of an anti-ulcerative colitis drug, characterized in that: Dissolve the amino acid and citric acid monohydrate in 50-100 mL of solvent at a mass ratio of 1 g:1 g to 1 g:5 g; Wherein, the solvent includes double distilled water and / or an organic solvent; the organic solvent includes N,N-dimethylformamide and ethanol.

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