Functionally modified coconut carbon dots, preparation method and application in antibacterial drugs

Abstract

The invention discloses a preparation method of functionally modified coconut carbon dots, which comprises the following steps: mixing coconut juice, a functional modification reagent and polyethylene glycol, reacting, cooling the reaction liquid, and dialyzing to obtain the functionally modified coconut carbon dots, the functional modification reagent is any one of a metal doped functional modification reagent, a light response functional modification reagent, an amination reagent or a quaternization reagent. According to the functional modified coconut carbon dots prepared by the preparation method, the preparation method is simple and convenient, natural antibacterial components contained in coconut juice are converted into nanoscale medicines with excellent antibacterial characteristics, and the specific surface area of medicine particles is effectively increased, so that the contact area of the medicines is increased, the interaction efficiency between the medicines and bacteria is improved, and the antibacterial activity of the medicines is improved. The antibacterial effect of the product is further enhanced and improved.

Description

Technical Field

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

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

[0003] Coconut is an evergreen tree of the genus Cocos in the palm family. Coconut mainly consists of coconut palm, coconut shell, coconut meat, and coconut water. Fresh coconuts can be eaten directly. Coconut water is a sweet and refreshing drink for relieving summer heat. Ripe coconut meat can be pressed for oil, containing up to 70% fat. Coconut fruits can also be processed into candies, beverages, pastries and other foods; Old fruits are suitable for processing into copra, coconut flakes, coconut milk, etc. Coconut juice and coconut meat also contain ingredients such as vitamin B1, vitamin E, vitamin C, potassium, calcium, magnesium, and various trace elements. Moreover, coconut contains components such as coconut water element, lauric acid, and various medium-chain fatty acids, all of which have significant antibacterial effects and are natural plant-derived antibacterial products. They not only have rich active ingredients but also are not prone to 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 amines contained in biomass such as coconut are beneficial to the self-doping of heteroatoms in carbon dots, and are an environmentally friendly, biocompatible, and cost-effective raw material for synthesizing carbon dots. At present, there are relatively few reports on effectively modifying the antibacterial properties of biomass materials by nanotechnology. Therefore, how to provide a preparation method for functionalized coconut carbon dots with excellent antibacterial effects and simple operation has important application value. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a functionalized coconut carbon dot with a simple, efficient preparation process and relatively excellent antibacterial effect.

[0006] To achieve the purpose of this invention, the following technical solutions are adopted: In the first aspect of the present invention, a preparation method for functionalized coconut carbon dots is provided. First, coconut juice, a functionalized modification reagent, and polyethylene glycol are pretreated to be uniformly mixed together, and then the mixed solution is placed in a reaction kettle for reaction. The obtained reaction solution can be cooled and dialyzed to obtain the functionalized coconut carbon dots.

[0007] In the present invention, natural antibacterial components such as coco-hydrogen, lauric acid, and various medium-chain fatty acids contained in the coconut water biomass resource are modified by nanotechnology, and the antibacterial components are transformed into nanoscale drugs with excellent antibacterial properties, which can effectively increase the specific surface area of the drug particles, thereby increasing the contact area of the drug and improving the interaction efficiency between the drug and bacteria, further enhancing the antibacterial effect.

[0008] In an alternative embodiment, the functionalized modification reagent is any one of a metal-doped functionalized modification reagent, a light-responsive functionalized modification reagent, an amination reagent, or a quaternization reagent.

[0009] In the present invention, a specific functionalized modification reagent is used to further improve the preparation efficiency and the antibacterial effect of the product.

[0010] In an alternative embodiment, the functionalized modification reagent is a quaternization reagent, and the quaternization reagent is dimethyldiallylammonium chloride.

[0011] In the present invention, when surface quaternary ammonium salt modification is performed on the functionalized modified coconut carbon dots, compared with other modification methods, the prepared functionalized modified coconut carbon dot material has a better antibacterial effect.

[0012] In an alternative embodiment, coconut juice: functionalized modification reagent: polyethylene glycol = (15 - 35) mL: (0.2 - 1.5) mg: (0.01 - 0.1) mL.

[0013] In an alternative embodiment, the reaction temperature of the reaction kettle is 180 - 240 °C, and the time is 8 - 15 h.

[0014] In an alternative embodiment, the pretreatment is a combined treatment of microwave and ultrasonic wave. The power of the microwave is 200 - 600 W, and the treatment time is 10 - 60 s; the power of the ultrasonic wave is 150 - 380 W, and the treatment time is 5 - 25 min.

[0015] In the present invention, the mixture of coconut juice, functionalized modification reagent, and polyethylene glycol is subjected to a combined treatment of microwave and ultrasonic wave, which can make the reaction raw material components fully mixed, increase the collision contact probability of each component, improve the subsequent reaction effect, and prepare an antibacterial material with better effect.

[0016] In an alternative embodiment, the temperature of the cooling is 20 - 35 °C.

[0017] In an alternative embodiment, the dialysis time is 48 - 96 h.

[0018] The second aspect of the present invention is to provide a functionalized coconut carbon dot.

[0019] The third aspect of the present invention is to provide an application of the functionalized coconut carbon dot in the preparation of antibacterial drugs.

[0020] Preferably, the molecular weight of the polyethylene glycol is 200 - 2000.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention develops a new and simple preparation method for functionalized coconut carbon dot materials, creatively combines the nanonization approach with the problem of improving the antibacterial performance of coconut water biomass materials, and further selects specific functionalized modification reagents to perform surface functionalization modification on the materials, thereby preparing coconut carbon dot materials with high antibacterial performance. Moreover, through nanotechnology, natural antibacterial components such as coco water element, lauric acid, and various medium-chain fatty acids contained in coconut water biomass resources are modified, converting the antibacterial components into nano-scale drugs with excellent antibacterial characteristics, which are not prone to generating drug resistance after use and have better antibacterial effects. Description of the Drawings

[0022] Figure 1 It is a graph showing the analysis results of the antibacterial effect of the coconut carbon dots prepared in Example 1 of the present invention.

[0023] Figure 2 It is a transmission electron microscope image of the coconut carbon dots prepared in Example 1 of the present invention.

[0024] Figure 3 It is the DLS particle size analysis result of the coconut carbon dots prepared in Example 1 of the present invention.

[0025] Figure 4 It is the ultraviolet-visible absorption spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0026] Figure 5 It is the fluorescence spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0027] Figure 6 It is the infrared spectrum of the coconut carbon dots prepared in Example 1 of the present invention.

[0028] Figure 7 It is the X-ray photoelectron spectroscopy of the coconut carbon dots prepared in Example 1 of the present invention.

[0029] Figure 8 It is the toxicity test result of the coconut carbon dots prepared in Example 1 of the present invention. Detailed Embodiments

[0030] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0031] The polydopamine involved below is a product with the model CS-202407-001 purchased from Guangzhou Chuangsai Biomedical Materials Co., Ltd.; the chitosan is a product with the model C804726 purchased from Shanghai Macklin Biochemical Co., Ltd.

[0032] Example 1 This example provides a dimethyldiallylammonium chloride-modified coconut carbon dot, and its preparation method is as follows: Take 25 mL of fresh coconut juice, 500 μg of dimethyldiallylammonium chloride and 10 μL of polyethylene glycol 200, mix them and place them in a reaction kettle with a polytetrafluoroethylene lining. Place the reaction kettle in a vacuum dryer and react at 200 °C for 10 h to obtain a reaction solution. After the reaction solution is cooled for 10 h to 25 °C, take it out for dialysis. Dialyze (MW: 3500Da) for 72 h, and then prepare by freeze-drying to obtain the dimethyldiallylammonium chloride-modified coconut carbon dot.

[0033] Example 2 This example provides a dimethyldiallylammonium chloride-modified coconut carbon dot, and its preparation method is as follows: Take 20 mL of fresh coconut juice, 800 μg of dimethyldiallylammonium chloride and 40 μL of polyethylene glycol 600, mix them and place them in a reaction kettle with a polytetrafluoroethylene lining. Place the reaction kettle in a vacuum dryer and react at 180 °C for 15 h to obtain a reaction solution. After the reaction solution is cooled for 8.5 h to 27 °C, take it out for dialysis. Dialyze (MW: 3500Da) for 50 h, and then prepare by freeze-drying to obtain the dimethyldiallylammonium chloride-modified coconut carbon dot.

[0034] Example 3 This example provides a dimethyldiallylammonium chloride-modified coconut carbon dot, and its preparation method is as follows: Take 28 mL of fresh coconut juice, 200 μg of dimethyldiallylammonium chloride and 25 μL of polyethylene glycol 800, mix them and place them in a reaction kettle with a polytetrafluoroethylene lining. Place the reaction kettle in a vacuum dryer and react at 240 °C for 8 h to obtain a reaction solution. After the reaction solution is cooled for 14 h to 23.5 °C, take it out for dialysis. Dialyze (MW: 3500Da) for 90 h, and then prepare by freeze-drying to obtain the dimethyldiallylammonium chloride-modified coconut carbon dot.

[0035] Example 4 This embodiment provides coconut carbon dots functionalized with metal doping modification. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that dimethyldiallylammonium chloride is replaced with an equal amount of silver nitrate, and the remaining processing steps and process parameters refer to Embodiment 1.

[0036] Embodiment 5 This embodiment provides coconut carbon dots functionalized with light response modification. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that dimethyldiallylammonium chloride is replaced with an equal amount of polydopamine, and the remaining processing steps and process parameters refer to Embodiment 1.

[0037] Embodiment 6 This embodiment provides amino-functionalized coconut carbon dots. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that dimethyldiallylammonium chloride is replaced with an equal amount of chitosan, and the remaining processing steps and process parameters refer to Embodiment 1.

[0038] Embodiment 7 This embodiment provides quaternized coconut carbon dots. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that dimethyldiallylammonium chloride is replaced with an equal amount of acrylamidotrimethylammonium chloride, and the remaining processing steps and process parameters refer to Embodiment 1.

[0039] Embodiment 8 This embodiment provides quaternized coconut carbon dots. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that dimethyldiallylammonium chloride is replaced with an equal amount of epichlorohydrinyltrimethylammonium chloride, and the remaining processing steps and process parameters refer to Embodiment 1.

[0040] Embodiment 9 This embodiment provides coconut carbon dots. The preparation process is the same as that in Embodiment 1, and the difference from Embodiment 1 is only that the mixing of coconut juice, dimethyldiallylammonium chloride and polyethylene glycol 200 is carried out under the condition of combined microwave-ultrasonic treatment. Among them, the conditions of microwave are: 350 W microwave treatment for 30 s; the conditions of ultrasonic are: 240 W ultrasonic treatment for 15 min. The treated mixed solution is placed in a reaction kettle with a polytetrafluoroethylene lining for subsequent treatment, and the treatment steps and process parameters refer to Embodiment 1.

[0041] Embodiment 10 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 2, and the difference from Example 2 is only that the mixing of coconut juice, dimethyldiallylammonium chloride and polyethylene glycol 600 is carried out under the condition of microwave-ultrasonic combined treatment. Among them, the conditions of microwave are: 220 W microwave treatment for 55 s; the conditions of ultrasonic are: 150 W ultrasonic treatment for 5 min. The treated mixed solution is placed in a reaction kettle with a polytetrafluoroethylene lining for subsequent treatment, and the treatment steps and process parameters refer to Example 2.

[0042] Example 11 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 3, and the difference from Example 3 is only that the mixing of coconut juice, dimethyldiallylammonium chloride and polyethylene glycol 800 is carried out under the condition of microwave-ultrasonic combined treatment. Among them, the conditions of microwave are: 500 W microwave treatment for 15 s; the conditions of ultrasonic are: 350 W ultrasonic treatment for 22 min. The treated mixed solution is placed in a reaction kettle with a polytetrafluoroethylene lining for subsequent treatment, and the treatment steps and process parameters refer to Example 3.

[0043] Comparative Example 1 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 1, and the difference from Example 1 is only that the reaction condition is to place the reaction kettle in a vacuum dryer at 150 °C for reaction for 8 h to obtain a reaction solution, and the rest of the operations and process parameters refer to Example 1.

[0044] Comparative Example 2 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 1, and the difference from Example 1 is only that the reaction condition is to place the reaction kettle in a vacuum dryer at 280 °C for reaction for 8 h to obtain a reaction solution, and the rest of the operations and process parameters refer to Example 1.

[0045] Comparative Example 3 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 9, and the difference from Example 9 is only that the mixing is carried out only under the condition of microwave. Among them, the conditions of microwave are: 400 W microwave treatment for 45 s. The microwave-treated mixed solution is placed in a reaction kettle with a polytetrafluoroethylene lining for subsequent treatment, and the treatment steps and process parameters refer to Example 9.

[0046] Comparative Example 4 This example provides a kind of coconut carbon dots. The preparation process is the same as that in Example 9, and the difference from Example 9 is only that the mixing is carried out only under the condition of ultrasonic. Among them, the conditions of ultrasonic are: 300 W ultrasonic treatment for 25 min. The ultrasonic-treated mixed solution is placed in a reaction kettle with a polytetrafluoroethylene lining for subsequent treatment, and the treatment steps and process parameters refer to Example 9.

[0047] Test Example 1 Antibacterial Effect Test Under aseptic conditions, after resuscitating methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2), they were respectively inoculated into LB medium, cultured with constant shaking at 37 °C for 12 h. An appropriate amount of the bacterial solution was taken and inoculated into a new LB medium, and after culturing with constant shaking at 37 °C for 12 h, it was reserved for use.

[0048] Take the cultured methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2) bacterial solutions, adjust the bacterial solution concentration to OD 600 = 0.5, rinse three times with sterile PBS and resuspend (8000 rpm, 5 min). Add the carbon dot materials prepared in Examples 1-11 and Comparative Examples 1-4 to the T144 and B2 bacterial solutions respectively. The final concentrations of the carbon dot materials in the T144 and B2 bacterial solutions are 16 μg / mL and 32 μg / mL respectively. After mixing and incubating at 37 °C for 24 h, shake well, absorb the bacterial solution, dilute it by the same multiple, and then take 100 μL each and spread it on LB solid medium. At the same time, set a blank control group as the bacterial solution without adding carbon dots for spreading. Each group has 3 parallels. After each group is inverted and cultured in a 37 °C constant temperature incubator for 24 h, colony counting is carried out, and the decline rate of the colony number in each group compared with the blank control group is calculated. The results are shown in Table 1. At the same time, the visualization analysis of Example 1 and the blank control group is carried out through a live / dead reagent staining test (SYTO 9 / PI), and the results are as Figure 1 shown.

[0049] Table 1 Antibacterial situation of coconut carbon dots in Examples 1-11 and Comparative Examples 1-4 Test 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% It can be seen from the data in the above table that: (1) It can be seen from Examples 1-6 that the functionalized modified coconut carbon dot material prepared by the present invention has excellent inhibitory effects on methicillin-resistant Staphylococcus aureus and Escherichia coli, showing significant antibacterial effects and bactericidal properties. Among them, the effect of quaternary ammonium modification is further superior to that of the functionalized modified coconut carbon dot materials prepared by the other three functionalizations.

[0050] (2) By comparing Example 1 with Examples 7-8, it can be seen that when other quaternary ammonium reagents are used to replace dimethyldiallylammonium chloride in Examples 7-8, the antibacterial effects of the finally prepared quaternary ammonium coconut carbon dots are all inferior to that of Example 1. It can be seen that using a specific quaternary ammonium reagent can further improve the antibacterial effect of the functionalized modified coconut carbon dot material prepared.

[0051] (3) By comparing Examples 9-11 with Examples 1-3 respectively, it can be seen that when the microwave and ultrasonic co-treatment method is used to pre-treat and mix the components of the raw materials for the synthesis of functionalized coconut carbon dots, the mixing degree of each reaction raw material component can be further promoted, the collision and contact probability of each component can be increased, and the subsequent reaction effect can be improved. The prepared functionalized coconut carbon dot material has better antibacterial effect.

[0052] (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 a specific range, the antibacterial effect of the prepared functionalized coconut carbon dot material 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 prepared functionalized coconut carbon dot material has better antibacterial effect.

[0053] (5) By comparing Example 9 with Comparative Examples 3-4, it can be seen that when only one of microwave and ultrasonic treatment methods is used to assist the mixing of each raw material in Examples 3-4, even if the treatment power is increased and the treatment time is extended, the antibacterial effect of the prepared carbon dot material is worse than that of Example 9. It can be seen that in the present invention, the microwave-ultrasonic combined treatment method is used to assist the mixing of each synthetic material of coconut carbon dots, which can further promote the subsequent synthesis reaction effect and prepare a carbon dot material product with better effect.

[0054] From Figure 1 the test results in it show that the colony numbers of methicillin-resistant Staphylococcus aureus (T144) and Escherichia coli (B2) in the plates of the Example 1 group (CD group in the figure) are significantly reduced compared with the control group (PBS group in the figure), and there are yellow fluorescent dots. It can be seen that the live bacteria (green) and dead bacteria (red) in the plates after the treatment of the Example 1 group are effectively fused, proving that the prepared carbon dot material in the present invention has excellent bactericidal performance.

[0055] Test Example 2 This test example characterized the functionalized coconut carbon dots prepared in Example 1.

[0056] The surface morphology of the functionalized coconut carbon dot material was analyzed by transmission electron microscopy, and the results are shown in Figure 2 From Figure 2 it can be seen that the carbon dot material prepared in Example 1 of this example has an obvious lattice structure, and the lattice fringe spacing is 0.21 nm, which is consistent with the (102) diffraction plane of sp 2 graphite carbon; The particle size distribution of the functionalized coconut carbon dot material was analyzed by a DLS analyzer, and the results are shown in Figure 3, the average particle size of the carbon dot material was measured to be 4.8 ± 0.32 nm; The ultraviolet absorption peak of the functionalized coconut carbon dot material was analyzed by an ultraviolet-visible absorption spectrometer, and the results are shown in Figure 4 , it can be seen that there is a typical absorption peak at 420 nm. Analysis shows that the absorption peak here is due to the π-π* transition of C-C or C-O, indicating the presence of a carbon core structure in the carbon dot material; at the same time, the optimal excitation wavelength of the coconut carbon dot material is 336 nm, and the optimal emission wavelength is 532 nm. The results are shown in Figure 5 .

[0057] The functional groups of the functionalized coconut carbon dot material were analyzed by a Fourier transform infrared spectrometer, and the results are shown in Figure 6 , as can be seen from the figure, stretching bands at 3367.6 cm -1 / 1512 cm -1 and 1192.0 cm -1 were observed, proving the presence of amide or -NH2. These stretching bands are attributed to N-H stretching / vibrational bending and C-N stretching vibration. The absorption peak of CD at 1479 cm -1 is the shear plane bending vibration of C-H in -N + (CH3) 2- , confirming that the carbon dot material was successfully functionalized with quaternary ammonium salt functional groups, and the quaternary ammonium salt-modified functionalized coconut carbon dot material was successfully prepared; The elemental content, chemical state, and chemical bonds in the functionalized coconut carbon dot material were analyzed by an X-ray photoelectron spectrometer. The results are as Figure 7 shown. The XPS spectrum shows that the carbon dot material mainly contains three elements: carbon (C), nitrogen (N), and oxygen (O), with proportions of 73.76%, 10.99%, and 14.28% respectively. It contains a carbon core and functional group structures such as quaternary ammonium groups (-N + (CH3) 2- ), carbonyl groups (C=O), and typical graphene carbon cores (C-C), further verifying the successful preparation of the quaternary ammonium salt-modified functionalized coconut carbon dot material.

[0058] Test Example 3 In this test example, the cytotoxicity of the functionalized coconut carbon dots prepared in Example 1 was tested.

[0059] The toxicity of the carbon dots to mouse macrophages RAW 264.7 was evaluated by the CCK8 method. Specifically, RAW 264.7 cells were seeded in a 96-well plate, and the cell density was adjusted to 5×10 4After culturing at 37 °C in an incubator containing 5% CO2 for 12 h, 100 μL of carbon dots prepared in Example 1 with 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, 0.01875 mg / mL) were added. At the same time, a control group (10% FBS DMEM medium + RAW 264.7 cells) and a blank group (DMEM medium containing 10% FBS) were set up. After all groups were placed in an incubator at 37 °C and 5% CO2 and co-incubated for another 24 h, 100 μL of 10% CCK8 culture solution was added to each well and incubated for 1 h, and the absorbance was measured at 450 nm using an enzyme-linked immunosorbent assay reader. The cell survival rate can be calculated by the following formula:

[0060] 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.

[0061] The cytotoxicity of the drug to the cells was evaluated according to the obtained cell survival rate (CV%). Each group was tested in parallel six times, and the average value was taken. The results are as Figure 7 shown.

[0062] 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 h was above 90%, indicating that the carbon dot material prepared in the present invention has low cytotoxicity and is suitable for use in the preparation of antibacterial fields and related drugs.

[0063] In the present invention, natural antibacterial components such as cocosin, lauric acid, and various medium-chain fatty acids contained in coconut water biomass resources are modified by nanotechnology, and the antibacterial components are transformed into nanoscale drugs with excellent antibacterial properties, which can effectively increase the specific surface area of the drug particles, thereby increasing the contact area of the drug and improving the interaction efficiency between the drug and bacteria, further enhancing the antibacterial effect; moreover, in the present invention, a large number of functional groups are efficiently modified on the surface of carbon dots using specific functionalization modification reagents, further improving the synthesis efficiency and the antibacterial effect of the product.

[0064] The applicant declares that the technical solution of the present invention is illustrated by the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0065] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0066] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

Claims

1. Preparation method of functionalized modified coconut carbon dots, characterized in that, First, the coconut juice, functionalized modification reagent, and polyethylene glycol are pretreated to make them uniformly mixed together, and then the mixed solution is placed in a reaction kettle for reaction. The obtained reaction solution can be cooled and dialyzed to obtain the functionalized modified coconut carbon dots. Among them, the functionalized modification reagent is any one of a metal-doped functionalized modification reagent, a photo-responsive functionalized modification reagent, an amination reagent, or a quaternization reagent.

2. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, The functionalized modification reagent is a quaternization reagent, and the quaternization reagent is dimethyldiallylammonium chloride.

3. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, Coconut juice: functionalized modification reagent: polyethylene glycol = (15 - 35) mL: (0.2 - 1.5) mg: (0.01 - 0.1) mL.

4. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, The reaction temperature of the reaction kettle is 180 - 240 °C, and the time is 8 - 15 h.

5. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, The pretreatment is a combined treatment of microwave-ultrasound. 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.

6. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, The temperature of the cooling is 20 - 35 °C.

7. The preparation method of the functionalized modified coconut carbon dots according to claim 1, characterized in that, The time of the dialysis is 48 - 96 h.

8. A functionalized modified coconut carbon dot prepared by the preparation method of the functionalized modified coconut carbon dot according to any one of claims 1 - 7.

9. An application of the functionalized modified coconut carbon dot according to claim 8 in the preparation of antibacterial drugs.

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