Functionally modified coconut carbon dots, preparation methods, and applications in antibacterial drugs

Abstract

The present invention discloses a method for preparing functionalized coconut carbon dots, comprising the steps of: mixing coconut milk, a functionalized modification agent, and polyethylene glycol, reacting the mixture, cooling the reaction solution, and dialyzing the mixture to obtain the functionalized coconut carbon dots; the functionalized modification agent is any one of a metal-doped functionalized modification agent, a photoresponsive functionalized modification agent, an amination agent, and a quaternization agent. The functionalized coconut carbon dots prepared by the present invention are not only simple to prepare, but also convert the natural antibacterial components contained in the coconut milk into nanoscale drugs with excellent antibacterial properties, effectively increasing the specific surface area of ​​the drug particles, thereby increasing the contact area of ​​the drug, improving the interaction efficiency between the drug and bacteria, and further enhancing the antibacterial effect of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials and relates to functionalized modified coconut carbon dots, a preparation method thereof and application thereof in antibacterial drugs. Background Art

[0002] Carbon dots (CDs), also known as carbon quantum dots or carbon nanodots, are a type of zero-dimensional carbon nanomaterial with significant fluorescence properties. They are composed of ultrafine, dispersed, quasi-spherical carbon nanoparticles with a size of less than 10 nm. They have unique optical properties, small size (1-10 nm), wide sources, easy surface functionalization, and high stability. They are widely used in bioimaging, catalysis, and sensing.

[0003] Coconut is an evergreen tree of the genus Cocos in the palm family. Coconut is mainly composed of coconut coir, coconut shell, coconut meat and coconut water. Fresh coconut fruit can be eaten directly, and coconut water is a sweet and delicious summer drink. Mature coconut meat can be used to extract oil, which contains up to 70% fat. Coconut fruit can also be processed into candy, beverages, pastries and other foods; old fruit is suitable for processing and producing dried coconut, coconut flakes, coconut milk, etc. Coconut juice and coconut meat also contain vitamin B1, vitamin E, vitamin C, potassium, calcium, magnesium and other ingredients as well as a variety of trace elements. In addition, coconut contains coconut water, lauric acid and a variety of medium-chain fatty acids, all of which have significant antibacterial effects. It is a natural plant-derived antibacterial product, not only rich in active ingredients, but also not easy to develop drug resistance after use. Therefore, coconut provides an important plant resource for the research and development of new antibacterial drugs.

[0004] The rich organic acids and biogenic polyamines found in biomass such as coconut facilitate the self-doping of heteroatoms in carbon dots, making them an environmentally friendly, biocompatible, and cost-effective raw material for carbon dot synthesis. Currently, there are relatively few reports on the effective antibacterial properties of biomass materials modified using nanotechnology. Therefore, developing a method for preparing functionalized coconut carbon dots with excellent antibacterial properties and ease of use is of great application value. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a functionalized coconut carbon dot with a simple and efficient preparation process and excellent antibacterial effect.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention is to provide a method for preparing functionalized modified coconut carbon dots. Coconut milk, a functional modification reagent, and polyethylene glycol are first pretreated to uniformly mix them together. The mixture is then placed in a reactor for reaction. The obtained reaction solution is cooled and dialyzed to obtain the functionalized modified coconut carbon dots.

[0008] In the present invention, natural antibacterial components such as cocoa butter, lauric acid and various medium-chain fatty acids contained in coconut water biomass resources are modified by nanotechnology, and the antibacterial components are converted into nanoscale drugs with excellent antibacterial properties. This can effectively increase the specific surface area of ​​the drug particles, thereby increasing the contact area of ​​the drug, improving the interaction efficiency between the drug and bacteria, and further enhancing the antibacterial effect.

[0009] In an optional embodiment, the functional modification reagent is any one of a metal-doped functional modification reagent, a photoresponsive functional modification reagent, an amination reagent or a quaternization reagent.

[0010] In the present invention, specific functional modification reagents are used to further improve the preparation efficiency and the antibacterial effect of the product.

[0011] In an optional embodiment, the functional modification reagent is a quaternary ammonium reagent, and the quaternary ammonium reagent is dimethyldiallylammonium chloride.

[0012] In the present invention, when the surface of the functionalized modified coconut carbon dots is modified with quaternary ammonium salt, the prepared functionalized modified coconut carbon dot material has a better antibacterial effect compared with other modification methods.

[0013] In an optional embodiment, coconut water: functional modification reagent: polyethylene glycol = (15-35) mL: (0.2-1.5) mg: (0.01-0.1) mL.

[0014] In an optional embodiment, the reaction temperature of the reactor is 180-240° C., and the reaction time is 8-15 hours.

[0015] In an optional embodiment, the pretreatment is a combined microwave-ultrasonic treatment, the microwave power is 200-600 W, and the treatment time is 10-60 s; the ultrasonic power is 150-380 W, and the treatment time is 5-25 min.

[0016] In the present invention, the coconut milk, functional modification reagent and polyethylene glycol are mixed by microwave-ultrasonic combined treatment, which can fully mix the reaction raw material components, increase the probability of collision and contact between the components, improve the subsequent reaction effect, and prepare an antibacterial material with better effect.

[0017] In an optional embodiment, the cooling temperature is 20-35°C.

[0018] In an optional embodiment, the dialysis time is 48 to 96 hours.

[0019] The second aspect of the present invention is to provide a functionalized coconut carbon dot.

[0020] The third aspect of the present invention is to provide an application of functionalized modified coconut carbon dots in the preparation of antibacterial drugs.

[0021] Preferably, the molecular weight of the polyethylene glycol is 200-2000.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention develops a new and simple preparation method of functionalized modified coconut carbon dot materials, creatively combines the nano-processing approach with the problem of improving the antibacterial properties of coconut water biomass materials, and further selects specific functional modification reagents to perform surface functional modification on the materials, thereby preparing coconut carbon dot materials with high antibacterial properties. In addition, natural antibacterial components such as cocoa butter, lauric acid and various medium-chain fatty acids contained in coconut water biomass resources are modified by nanotechnology, and the antibacterial components are converted into nano-scale drugs with excellent antibacterial properties. The drugs are not easy to produce drug resistance after use, and the antibacterial effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is an analysis result of the antibacterial effect of coconut carbon dots prepared in Example 1 of the present invention.

[0025] Figure 2 1 is a transmission electron micrograph of coconut carbon dots prepared in Example 1 of the present invention.

[0026] Figure 3 This is the DLS particle size analysis result of the coconut carbon dots prepared in Example 1 of the present invention.

[0027] Figure 4 This is the UV-visible absorption spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0028] Figure 5 This is a fluorescence spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0029] Figure 6 This is an infrared spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0030] Figure 7 This is an X-ray photoelectron spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0031] Figure 8 This is the toxicity test result of the coconut carbon dots prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0033] The polydopamine mentioned below is the product model CS-202407-001 purchased from Guangzhou Chuangsai Biomedical Materials Co., Ltd.; the chitosan is the product model C804726 purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0034] Example 1

[0035] This embodiment provides a coconut carbon dot modified with dimethyldiallylammonium chloride, and the preparation method thereof is as follows:

[0036] 25 mL of fresh coconut water, 500 μg of dimethyldiallylammonium chloride and 10 μL of polyethylene glycol 200 were mixed and placed in a reactor lined with polytetrafluoroethylene. The reactor was placed in a vacuum desiccator and reacted at 200°C for 10 h to obtain a reaction solution. The reaction solution was cooled to 25°C for 10 h and then dialyzed (MW: 3500Da) for 72 h. The solution was freeze-dried to obtain coconut carbon dots modified with dimethyldiallylammonium chloride.

[0037] Example 2

[0038] This embodiment provides a coconut carbon dot modified with dimethyldiallylammonium chloride, and the preparation method thereof is as follows:

[0039] 20 mL of fresh coconut water, 800 μg of dimethyldiallylammonium chloride and 40 μL of polyethylene glycol 600 were mixed and placed in a reactor lined with polytetrafluoroethylene. The reactor was placed in a vacuum desiccator and reacted at 180°C for 15 h to obtain a reaction solution. The reaction solution was cooled to 27°C for 8.5 h and then dialyzed (MW: 3500Da) for 50 h. The coconut carbon dots modified with dimethyldiallylammonium chloride were obtained by freeze-drying.

[0040] Example 3

[0041] This embodiment provides a coconut carbon dot modified with dimethyldiallylammonium chloride, and the preparation method thereof is as follows:

[0042] 28 mL of fresh coconut water, 200 μg of dimethyldiallylammonium chloride, and 25 μL of polyethylene glycol 800 were mixed and placed in a reactor lined with polytetrafluoroethylene. The reactor was placed in a vacuum desiccator and reacted at 240°C for 8 h to obtain a reaction solution. The reaction solution was cooled to 23.5°C for 14 h, then dialyzed (MW: 3500Da) for 90 h and freeze-dried to prepare coconut carbon dots modified with dimethyldiallylammonium chloride.

[0043] Example 4

[0044] This example provides metal-doped functionalized coconut carbon dots. The preparation process is the same as that of Example 1. The only difference from Example 1 is that dimethyldiallylammonium chloride is replaced with an equal amount of silver nitrate. The remaining processing steps and process parameters refer to those of Example 1.

[0045] Example 5

[0046] This embodiment provides a photoresponsive functionalized coconut carbon dots. The preparation process is the same as that of Example 1. The only difference from Example 1 is that dimethyldiallylammonium chloride is replaced with an equal amount of polydopamine. The remaining processing steps and process parameters refer to Example 1.

[0047] Example 6

[0048] This embodiment provides an amino coconut carbon dot. The preparation process is the same as that of Example 1. The only difference from Example 1 is that dimethyldiallylammonium chloride is replaced by an equal amount of chitosan. The remaining processing steps and process parameters refer to Example 1.

[0049] Example 7

[0050] This embodiment provides a quaternized coconut carbon dot. The preparation process is the same as that of Example 1. The only difference from Example 1 is that dimethyldiallylammonium chloride is replaced with an equal amount of acrylamidotrimethylammonium chloride. The remaining processing steps and process parameters are the same as those of Example 1.

[0051] Example 8

[0052] This embodiment provides a quaternized coconut carbon dot. The preparation process is the same as that of Example 1. The only difference from Example 1 is that dimethyldiallylammonium chloride is replaced with an equal amount of epichlorohydrin trimethylammonium chloride. The remaining processing steps and process parameters are the same as those of Example 1.

[0053] Example 9

[0054] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 1. The only difference from Example 1 is that the mixing of the coconut milk, dimethyldiallylammonium chloride, and polyethylene glycol 200 is carried out under conditions of microwave-ultrasonic combined treatment, wherein the microwave conditions are: 350 W microwave treatment for 30 s; the ultrasonic conditions are: 240 W ultrasonic treatment for 15 min. The treated mixed solution is placed in a reactor lined with polytetrafluoroethylene for subsequent treatment. The treatment steps and process parameters are referred to in Example 1.

[0055] Example 10

[0056] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 2. The only difference from Example 2 is that the mixing of the coconut milk, dimethyldiallylammonium chloride, and polyethylene glycol 600 is carried out under conditions of microwave-ultrasonic combined treatment, wherein the microwave conditions are: 220 W microwave treatment for 55 s; the ultrasonic conditions are: 150 W ultrasonic treatment for 5 min. The treated mixed solution is placed in a reactor lined with polytetrafluoroethylene for subsequent treatment. The treatment steps and process parameters are referred to in Example 2.

[0057] Example 11

[0058] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 3. The only difference from Example 3 is that the mixing of the coconut milk, dimethyldiallylammonium chloride, and polyethylene glycol 800 is carried out under conditions of microwave-ultrasonic combined treatment, wherein the microwave conditions are: 500 W microwave treatment for 15 s; the ultrasonic conditions are: 350 W ultrasonic treatment for 22 min. The treated mixed solution is placed in a reactor lined with polytetrafluoroethylene for subsequent treatment. The treatment steps and process parameters are referred to in Example 3.

[0059] Comparative Example 1

[0060] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 1. The only difference from Example 1 is that the reaction conditions are to place the reactor in a vacuum desiccator at 150° C. for 8 h to obtain a reaction solution. The remaining operations and process parameters are the same as those of Example 1.

[0061] Comparative Example 2

[0062] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 1. The only difference from Example 1 is that the reaction conditions are to place the reactor in a vacuum desiccator at 280°C for 8 hours to obtain a reaction solution. The remaining operations and process parameters are the same as those of Example 1.

[0063] Comparative Example 3

[0064] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 9. The only difference from Example 9 is that the mixing is performed only under microwave conditions, wherein the microwave conditions are: microwave treatment at 400 W for 45 s. The mixed solution after microwave treatment is placed in a reactor lined with polytetrafluoroethylene for subsequent treatment. The treatment steps and process parameters are referred to in Example 9.

[0065] Comparative Example 4

[0066] This embodiment provides coconut carbon dots, and the preparation process is the same as that of Example 9. The only difference from Example 9 is that the mixing is performed only under ultrasonic conditions, wherein the ultrasonic conditions are: 300 W ultrasonic treatment for 25 minutes, and the ultrasonically treated mixed solution is placed in a reactor lined with polytetrafluoroethylene for subsequent treatment. The processing steps and process parameters are referred to in Example 9.

[0067] Test Example 1

[0068] Antibacterial effect test

[0069] Under sterile conditions, methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2) were revived and inoculated into LB medium respectively, and cultured at 37°C with shaking for 12 h. An appropriate amount of bacterial liquid was inoculated into new LB medium, and cultured at 37°C with shaking for 12 h before use.

[0070] Take the cultured methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2) bacterial suspension and adjust the bacterial suspension concentration to OD 600 =0.5, rinsed three times with sterile PBS and resuspended (8000 rpm, 5 min), took the carbon dot materials prepared in Examples 1-11 and Comparative Examples 1-4 and added them to T144 and B2 bacterial solutions, respectively, where the final concentrations of the carbon dot materials in T144 and B2 bacterial solutions were 16 μg / mL and 32 μg / mL, respectively. After mixing, incubated at 37°C for 24 h, the bacterial solution was shaken and aspirated, diluted by the same multiple, and 100 μL was taken from each to be coated on LB solid culture medium. At the same time, a blank control group was set up for coating with bacterial solution without carbon dots added. Each group had 3 parallels, and each group was incubated in an inverted incubator at 37°C for 24 h. After that, the colonies were counted and the decrease rate of the colony number in each group compared with the blank control group was calculated. The results are shown in Table 1. At the same time, Example 1 and the blank control group were visualized by live-dead reagent staining test (SYTO 9 / PI). The results are shown in Table 1. Figure 1 shown.

[0071] Table 1 Antibacterial performance of coconut carbon dots in Examples 1-11 and Comparative Examples 1-4

[0072] Testing carbon dots Methicillin-resistant Staphylococcus aureus (T144) Escherichia coli (B2) Example 1 52.55% 61.65% Example 2 51.62% 60.36% Example 3 52.08% 61.45% Example 4 40.12% 45.37% Example 5 35.86% 40.15% Example 6 42.35% 46.48% Example 7 43.25% 48.73% Example 8 44.62% 46.91% Example 9 54.76% 64.58% Example 10 53.55% 62.56% Example 11 53.95% 62.80% Comparative Example 1 46.26% 54.58% Comparative Example 2 45.38% 52.94% Comparative Example 3 50.74% 59.87% Comparative Example 4 49.92% 58.02%

[0073] From the data in the above table, we can see that:

[0074] (1) It can be seen from Examples 1-6 that the functionalized coconut carbon dot materials prepared by the present invention have excellent inhibitory effects on methicillin-resistant Staphylococcus aureus and Escherichia coli, and show significant antibacterial and bactericidal properties. Among them, the effect of quaternary ammonium modification is further better than that of the functionalized coconut carbon dot materials prepared by the other three functional modifications.

[0075] (2) By comparing Example 1 with Examples 7-8, it can be seen that when other quaternizing agents are used to replace dimethyldiallylammonium chloride in Examples 7-8, the antibacterial effects of the quaternized coconut carbon dots finally prepared are not as good as those in Example 1. It can be seen that the use of specific quaternizing agents can further enhance the antibacterial effects of the functionalized modified coconut carbon dot materials prepared.

[0076] (3) By comparing Examples 9-11 with Examples 1-3, it can be seen that when the various synthetic raw material components of the functionalized modified coconut carbon dots are pre-treated and mixed by microwave combined with ultrasonic co-treatment, the degree of mixing between the various reaction raw material components can be further promoted, the probability of collision and contact between the components can be increased, and the subsequent reaction effect can be improved, thereby preparing the functionalized modified coconut carbon dot material with better antibacterial effect.

[0077] (4) By comparing Example 1 with Comparative Examples 1-2, it can be seen that when the synthesis reaction temperature used in Comparative Examples 1-2 is not within the specific range, the antibacterial effect of the functionalized modified coconut carbon dot material prepared therefrom is worse than that of Example 1. It can be seen that when a specific synthesis reaction temperature is used in the present invention, the functionalized modified coconut carbon dot material prepared therefrom has a better antibacterial effect.

[0078] (5) By comparing Example 9 with Comparative Examples 3-4, it can be seen that when only one of the microwave and ultrasonic treatment methods is used to assist the mixing of the raw materials in Examples 3-4, even if the treatment power is increased and the treatment time is extended, the antibacterial effect of the carbon dot material prepared is worse than that of Example 9. It can be seen that the use of microwave-ultrasonic combined treatment to assist the mixing of the coconut carbon dot synthetic materials in the present invention can further promote the subsequent synthetic reaction effect and prepare a carbon dot material product with better effect.

[0079] Depend on Figure 1 The test results show that the colony counts of methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2) in the plates of Example 1 group (CD group in the figure) were significantly reduced compared with those in the control group (PBS group in the figure), and yellow fluorescent spots were present. It can be seen that the live bacteria (green) and dead bacteria (red) in the plates treated with Example 1 group were effectively fused, proving that the carbon dot material prepared in the present invention has excellent bactericidal properties.

[0080] Test Example 2

[0081] This test example performs material characterization on the functionalized modified coconut carbon dots prepared in Example 1.

[0082] The surface morphology of the functionalized coconut carbon dot material was analyzed by transmission electron microscopy. Figure 2 ,Depend on Figure 2 It can be seen that the carbon dot material prepared in Example 1 has a clear lattice structure, and the lattice fringe spacing is 0.21 nm, which is consistent with the sp 2 The (102) diffraction plane of graphitic carbon is consistent;

[0083] The particle size distribution of the functionalized coconut carbon dot material was analyzed by DLS analyzer. Figure 3 , the average particle size of the carbon dot material was measured to be 4.8 ± 0.32 nm;

[0084] The UV absorption peak of the functionalized coconut carbon dot material was analyzed by UV-visible absorption spectrometer. The results are shown in Figure 4 , it can be seen that it has a typical absorption peak at 420 nm. Analysis shows that the absorption peak here is due to the π-π* transition of CC or CO, indicating that there is a carbon core structure in the carbon dot material; at the same time, the optimal excitation wavelength of coconut carbon dot material is 336 nm, and the optimal emission wavelength is 532 nm. The results are shown in Figure 5 .

[0085] The functional groups of the functionalized coconut carbon dot materials were analyzed by Fourier transform infrared spectroscopy. Figure 6 As can be seen from the figure, a 3367.6 cm -1 / 1512 cm -1 and 1192.0 cm -1 The stretching bands at 1479 cm-1 indicate the presence of amide or -NH2. These stretching bands are attributed to NH stretching / vibration bending and CN stretching vibration. -1 The absorption peak at -N + (CH3) 2- The shear plane bending vibration in the carbon dot material confirmed that the carbon dot material was successfully functionalized with the quaternary ammonium salt functional group, and the quaternary ammonium salt-modified coconut carbon dot material was successfully prepared;

[0086] The element content, chemical state and chemical bond of the functionalized coconut carbon dot material were analyzed by X-ray photoelectron spectroscopy. Figure 7 As shown in the XPS spectrum, the carbon dot material mainly contains carbon (C), nitrogen (N) and oxygen (O), with a ratio of 73.76%, 10.99% and 14.28% respectively. + (CH3) 2- ), carbonyl (C=O) and typical graphene carbon core (CC) and other functional group structures, further verifying the successful preparation of quaternary ammonium salt-modified functionalized coconut carbon dot materials.

[0087] Test Example 3

[0088] In this test example, the functionalized modified coconut carbon dots prepared in Example 1 were subjected to a cytotoxicity test.

[0089] The cytotoxicity of carbon dots to mouse macrophage RAW 264.7 cells was evaluated by CCK8 assay. Specifically, RAW 264.7 cells were seeded in 96-well plates and the cell density was adjusted to 5×10 4 After culturing for 12 h at 37°C in a 5% CO2 incubator, 100 μL of the carbon dots prepared in Example 1 were added at a series of concentrations (final concentrations of 1 mg / mL, 0.8 mg / mL, 0.5 mg / mL, 0.25 mg / mL, 0.125 mg / mL, 0.0625 mg / mL, 0.0375 mg / mL, and 0.01875 mg / mL). A control group (10% FBS DMEM medium + RAW 264.7 cells) and a blank group (DMEM medium containing 10% FBS) were also set up. All groups were placed in a 37°C, 5% CO2 incubator and incubated again for 24 h. After that, 100 μL of 10% CCK8 culture medium was added to each well and incubated for 1 h. The absorbance was measured at 450 nm using a microplate reader. The cell viability rate can be calculated using the following formula:

[0090]

[0091] Where As is the absorbance of the experimental group, Ab is the absorbance of the blank group, and Ac is the absorbance of the control group.

[0092] The toxicity of the drug to the cells was evaluated based on the obtained cell survival rate (CV%). Each group was tested six times in parallel and the average value was taken. The results are shown in the figure. Figure 7 shown.

[0093] from Figure 8 It can be seen that the survival rate of RAW 264.7 cells after incubation with carbon dots at different concentrations for 24 hours is above 90%, indicating that the carbon dot material prepared by the present invention has low cytotoxicity and is suitable for use in the antibacterial field and the preparation of related drugs.

[0094] In the present invention, natural antibacterial components such as coconut water, lauric acid and various medium-chain fatty acids contained in coconut water biomass resources are modified by nanotechnology, and the antibacterial components are converted into nanoscale drugs with excellent antibacterial properties. This can effectively increase the specific surface area of ​​the drug particles, thereby increasing the contact area of ​​the drug, improving the efficiency of its interaction with bacteria, and further enhancing the antibacterial effect. In addition, the present invention uses specific functional modification reagents to efficiently modify a large number of functional groups on the surface of carbon dots, further improving the synthesis efficiency and the antibacterial effect of the product.

[0095] The applicant declares that the present invention is illustrated by the above-described embodiments, but the present invention is not limited to the above-described embodiments. This does not mean that the present invention must rely on the above-described embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0096] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0097] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing functionalized coconut carbon dots, characterized in that: Coconut milk, a functional modification reagent, and polyethylene glycol are pretreated to uniformly mix the mixture, and then the mixture is placed in a reactor and reacted at a temperature of 180 to 240° C. for 8 to 15 hours. The obtained reaction solution is cooled and dialyzed to obtain the functionalized coconut carbon dots. Among them, coconut water: functional modification reagent: polyethylene glycol = (15-35) mL: (0.2-1.5) mg: (0.01-0.1) mL; Wherein, the functional modification reagent is dimethyldiallylammonium chloride.

2. The method for preparing functionalized coconut carbon dots according to claim 1, wherein The pretreatment is a combined microwave-ultrasonic treatment, wherein the power of the microwave is 200-600 W and the treatment time is 10-60 s; the power of the ultrasound is 150-380 W and the treatment time is 5-25 min.

3. The method for preparing functionalized coconut carbon dots according to claim 1, wherein The cooling temperature is 20-35°C.

4. The method for preparing functionalized coconut carbon dots according to claim 1, wherein The dialysis time is 48 to 96 hours. 5 . Functionalized modified coconut carbon dots prepared according to the method for preparing functionalized modified coconut carbon dots according to any one of claims 1 to 4 .

6. Use of the functionalized coconut carbon dots according to claim 5 in the preparation of antibacterial drugs.

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