1. The preparation method of the carbon quantum dot is characterized in that citric acid and mercaptoethylamine are subjected to hydrothermal reaction in deionized water, and then dialysis and freeze drying are carried out to obtain the carbon quantum dot S, N-CQDs.

2. The method for preparing carbon quantum dots according to claim 1, wherein the mass-to-volume ratio of the citric acid, the mercaptoethylamine and the deionized water is 0.4-0.8 g: 1-4 g: 30-45 mL.

3. The method for preparing a carbon quantum dot as defined in claim 1, wherein the reaction temperature of the hydrothermal reaction is 130-180 ℃ and the reaction time is 120-200 min.

4. The method for preparing carbon quantum dots according to claim 1, wherein the dialysis is performed in a dialysis bag for 36-72h, and water is replaced every 4-6h during dialysis.

5. A carbon quantum dot, wherein the carbon quantum dot is prepared by the preparation method according to any one of claims 1 to 5.

6. A high-efficiency antibacterial material containing nano-silver based on carbon quantum dots, which is characterized in that the high-efficiency antibacterial material is prepared based on the carbon quantum dots S, N-CQDs as claimed in claim 5.

7. A preparation method of a high-efficiency antibacterial material containing nano-silver based on carbon quantum dots is characterized in that the preparation method comprises the steps of mixing and stirring a carbon quantum dot S, N-CQDs aqueous solution prepared from the carbon quantum dots S, N-CQDs of claim 5 with a silver nitrate aqueous solution, and obtaining the high-efficiency antibacterial material AgNPs @ S, N-CQDs after reduction reaction, dialysis and freeze drying.

8. The method for preparing the nano-silver containing high-efficiency antibacterial material based on the carbon quantum dots according to claim 7, wherein the mass volume concentration of the water solution of the carbon quantum dots S, N-CQDs is 0.5-2.5 mg/mL.

9. The method for preparing the efficient antibacterial material containing the nano-silver based on the carbon quantum dots according to claim 7, wherein the mass volume concentration of the silver nitrate aqueous solution is 15-25 mg/mL.

10. The method for preparing the efficient antibacterial material containing the nano-silver based on the carbon quantum dots according to claim 7, wherein the mass ratio of the silver nitrate solution to the carbon quantum dot S, N-CQDs solution is any one of 4:1,2:1,1: 2 and 1: 4.

Background

Bacteria are widely present in daily life environments, and currently, only a large amount of antibiotics are used for treating bacterial infection, but antibiotic-resistant strains are inevitably generated when the bacterial infection is treated by the antibiotics, for example, methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant staphylococcus aureus (VRSA) are generated when the bacterial infection is treated, so that the infection is increased, the life is threatened, and the public health is seriously burdened. Many materials with high antibacterial activity have been presented for antibacterial or bacterial killing purposes, such as quaternary ammonium compounds, metal ions or oxides and antibacterial peptides, wherein the antibacterial peptides have good antibacterial performance, and the quaternary ammonium compounds, metal ions and other materials can reduce or inhibit the activity of microorganisms or bacteria, and the materials are limited in wide use due to the defects of high cost, complex synthesis, low antibiotic resistance or biocompatibility and the like.

In recent years, nanotechnology has become an ideal material for developing a new generation of antibacterial applications, and the nano-silver inactivated by bacteria has high bactericidal power and relatively low cost, can slowly release silver ions, can react with active partial sulfydryl, amino and the like on enzyme protein in bacterial cells, so that the enzyme protein precipitates and loses activity, the respiratory metabolism of pathogenic bacteria is forced to stop, and the growth and the propagation of bacteria are inhibited, thereby becoming a hotspot of research. For higher antibacterial effect, some silver-doped dressings or ointments have extremely strong biological toxicity, and how to control the amount of released silver ions becomes the main problem of the Ag NPs antibacterial agent, compared with the traditional silver antibacterial preparations such as silver sulfadiazine and the like, the nano-silver antibacterial material is relatively safer, the toxicity of nano-silver is reported to be much lower than that of silver, and the nano-silver has no obvious toxic effect on gene expression when exposed in nano-silver with the concentration of 0.5 mg/mL. The invention patent with Chinese patent publication No. CN112806389A discloses a preparation method of a graphene oxide/silver nano composite hybrid antibacterial material, firstly, preparing nano silver by using amino-terminated hyperbranched polymer to regulate and control, and obtaining nano silver dispersion liquid coated with a large amount of amino; then, epoxy chloropropane is used as an intermediate, graphene oxide is firstly modified to have reaction activity, and then the modified graphene oxide reacts with aminated nano silver to graft the nano silver onto the graphene oxide, so that the nano silver is uniformly and stably fixed on a graphene oxide lamella, and the graphene oxide/nano silver composite hybrid material is obtained; finally, the functional finishing of the graphene oxide/nano-silver composite hybrid antibacterial material on the textile is realized based on the principle of nano self-assembly; the processing technology is simple and convenient, and the obtained functional textile has excellent antibacterial and antiviral effects. In addition, the Chinese journal is published in the high polymer materials science and engineering by the synthetic and preparation of chitosan oligosaccharide modified nano-silver as an antibacterial material, such as Luoquanjin, volume 32, No. 2, pages 13-18 in 2016, and discloses a synthetic and preparation method of chitosan oligosaccharide modified nano-silver as an antibacterial material.

Carbon quantum dots CQDs are novel metal-free fluorescent nanoparticles, have the advantages of simple synthesis, low toxicity, good biocompatibility, easy surface modification and the like, and become a hot point of research, the carbon quantum dots CQDs are composed of a part of nanoscale carbon cores surrounded by an amorphous carbon framework, part of functional groups such as amino, hydroxyl and carboxyl existing on the surface can be used as reaction points, and the carbon quantum dots CQDs have been widely applied in various fields such as imaging, sensing, catalysis and the like. Methods for synthesizing CQDs are mainly divided into two categories: 1) the top-down approach refers to a preparation method of CQDs for decomposing larger carbon materials by chemical oxidation, laser ablation or electrochemical synthesis; 2) the bottom-up approach involves the preparation of CQDs from smaller precursors using hydrothermal/solvothermal treatment, microwave/ultrasonication or plasma treatment.

The invention utilizes the special action between the silver nano particles and the carbon quantum dots to prepare the high-efficiency antibacterial material, can well realize the synergistic action of the nano silver and the carbon quantum dots on antibacterial property, improves the antibacterial performance, simultaneously solves the biotoxicity of single silver ions, improves the biocompatibility and the application range of the material, and has strong bactericidal action on antibiotic drug-resistant bacteria.

Disclosure of Invention

The invention aims to provide a carbon quantum dot and a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot, and the high-efficiency antibacterial composite material based on the interaction of silver nanoparticles and the carbon quantum dot is constructed, the carbon quantum dot has a strong fluorescence phenomenon and strong reducibility, and the constructed high-efficiency antibacterial composite material has broad-spectrum antibacterial activity when being applied to the antibacterial aspect, has stronger antibacterial performance compared with single AgNPs and S, has a better antibacterial effect especially on antibiotic drug-resistant bacteria, has a better antibacterial effect, and can well solve the problem of antibiotic drug-resistant strains.

The invention also aims to provide the carbon quantum dots and the preparation method of the high-efficiency antibacterial material containing nano silver based on the carbon quantum dots, and the preparation method has the advantages of simple preparation method, easily obtained raw materials, environmental friendliness, suitability for mass production and the like.

The technical scheme adopted by the invention to achieve the aim is as follows:

a preparation method of carbon quantum dots comprises the steps of carrying out hydrothermal reaction on citric acid and mercaptoethylamine in deionized water, dialyzing, and carrying out freeze drying to obtain the carbon quantum dots S, N-CQDs.

In the further concrete implementation process, the mass volume ratio of the citric acid to the mercaptoethylamine to the deionized water is 0.4-0.8 g: 1-4 g: 30-45 mL.

In a further specific implementation process, the reaction temperature of the hydrothermal reaction is 130-180 ℃ and the reaction time is 120-200 min.

In a further specific implementation process, the dialysis is carried out in the dialysis bag for 36-72h, and water is replaced every 4-6h in the dialysis process.

The carbon quantum dot is prepared by the preparation method.

The invention relates to a high-efficiency antibacterial material containing nano-silver based on carbon quantum dots, which is prepared based on the carbon quantum dots S, N-CQDs.

The invention relates to a preparation method of a high-efficiency antibacterial material containing nano-silver based on carbon quantum dots, which is characterized in that a carbon quantum dot S, N-CQDs aqueous solution prepared from the obtained carbon quantum dots S, N-CQDs is mixed and stirred with a silver nitrate aqueous solution, and the high-efficiency antibacterial material AgNPs @ S, N-CQDs is obtained after reduction reaction, dialysis and freeze drying.

In a further specific implementation process, the mass volume concentration of the carbon quantum dot S, N-CQDs aqueous solution is 0.5-2.5 mg/mL.

In a further specific implementation process, the mass volume concentration of the silver nitrate aqueous solution is 15-25 mg/mL.

In a further specific implementation process, the mass ratio of the silver nitrate solution to the carbon quantum dot S and N-CQDs solution is any one of 4:1,2:1,1: 2 and 1: 4.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention utilizes hydrothermal reaction to construct the doped carbon quantum dot containing C, O, S, N four elements by a simple hydrothermal method, and the carbon quantum dot has strong fluorescence phenomenon and strong reducibility; the prepared doped carbon quantum dots are reacted with silver nitrate, and the doped carbon quantum dots and the silver nitrate are mixed by a simple mixing method to generate silver nanoparticles, so that the efficient antibacterial composite material with the interaction of the silver nanoparticles and the doped carbon quantum dots is synthesized. The S, N-CQDs containing S, N two kinds of miscellaneous elements are prepared by citric acid and mercaptoethylamine based on a hydrothermal reaction, silver ions are reduced into silver nanoparticles by sulfydryl and amino on the S, N-CQDs, a special acting force is formed between the silver nanoparticles and carbon quantum dots, and the efficient antibacterial composite material of the silver nanoparticles and the carbon quantum dots is generated, so that the aim of slowly releasing silver is fulfilled, an efficient antibacterial effect is achieved, and the advantage of resisting antibiotic-resistant bacteria is more prominent.

2. The carbon quantum dot and the efficient antibacterial material thereof have the advantages of simple preparation method, easily obtained raw materials, environmental protection compliance, suitability for mass production and the like.

3. The high-efficiency antibacterial composite material constructed by the invention is applied to the antibacterial aspect, has good and strong antibacterial action on common gram-positive bacteria, common bacteria, gram-negative bacteria, fungi and antibiotic-resistant bacteria, has broad-spectrum antibacterial activity, particularly has outstanding antibacterial effect on the antibiotic-resistant bacteria, can well solve the problem of abuse of antibiotics, has incomparable advantages and strong practical value, and has wide application prospect.

Drawings

FIG. 1 is a graph showing the infrared absorption curves of the carbon quantum dots S, N-CQDs and the high-efficiency antibacterial material AgNPs @ S, N-CQDs of the present embodiment;

FIG. 2 is a TEM image of the high-efficiency antibacterial material AgNPs @ S, N-CQDs of the present embodiment;

FIG. 3 is a schematic diagram of the plate experiment bacteriostasis rate of the carbon quantum dots S, N-CQDs and the highly effective antibacterial material Ag NPs @ S, N-CQDs co-cultured with different bacteria under different concentration conditions.

The specific implementation mode is as follows:

in order to better explain the present invention and to facilitate the understanding of the technical solutions of the present invention, the present invention is first described in further detail. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The specific embodiment of the invention provides a carbon quantum dot and a preparation method thereof, wherein citric acid and mercaptoethylamine are subjected to hydrothermal reaction in deionized water, and then dialyzed and freeze-dried to obtain the carbon quantum dot S, N-CQDs. The carbon quantum dots have strong fluorescence phenomenon and strong reducibility; the prepared doped carbon quantum dots are reacted with silver nitrate, and the doped carbon quantum dots and the silver nitrate are mixed by a simple mixing method to generate silver nanoparticles, so that the efficient antibacterial composite material with the interaction of the silver nanoparticles and the doped carbon quantum dots is synthesized.

The specific embodiment of the invention also provides a high-efficiency antibacterial material containing nano-silver based on carbon quantum dots and a preparation method thereof, the carbon quantum dots S, N-CQDs are prepared into an aqueous solution to be mixed and stirred with a silver nitrate aqueous solution, silver ions are reduced to prepare silver nano-particles and a high-efficiency antibacterial composite material containing carbon quantum dots, and the high-efficiency antibacterial composite material AgNPs @ S, N-CQDs is obtained after reduction reaction, dialysis and freeze drying.

Preferably, the dialysis process is performed in the dialysis bag for a dialysis time of 48, and the water is changed every 6 intervals during the dialysis process.

The following are typical but non-limiting examples of the invention:

example 1:

the embodiment provides carbon quantum dots S, N-CQDs and a preparation method thereof, and the specific steps comprise:

weighing 0.684g of mercaptoethylamine and 2.1g of citric acid, dissolving in 35mL of deionized water, placing in a stainless steel reaction kettle after being filled in a polytetrafluoroethylene lining, carrying out hydrothermal reaction for 180min at 150 ℃ to obtain a light yellow solution, dialyzing by using a dialysis bag for 48h to remove unreacted mercaptoethylamine and citric acid, changing water once at intervals of 6h, and freezing and drying the final solution to obtain a light yellow solid. Dissolving the obtained light yellow solid with deionized water, preparing into solution with certain concentration, and storing at room temperature for use; the carbon quantum dots S, N-CQDs prepared by the embodiment have stronger fluorescence under the irradiation of ultraviolet light UV wavelength of 365 nm. The obtained carbon quantum dots S, N-CQDs contain sulfydryl, have reducibility, can reduce silver ions into silver nanoparticles, and form a high-efficiency antibacterial composite material with the carbon quantum dots S, N-CQDs to generate high-efficiency antibacterial action.

Example 2:

the embodiment provides a carbon quantum dot-based nano-silver-containing efficient antibacterial material and a preparation method thereof, and the specific steps comprise:

weighing a certain mass of the carbon quantum dots S, N-CQDs, dissolving in deionized water to obtain a solution with the concentration of 1mg/mL and 100mL in total, then weighing a silver nitrate solution with a certain concentration of 20mg/mL and 5mL in total, adding the solution into the solution of the carbon quantum dots S, N-CQDs under the condition of magnetic stirring, continuously stirring for 48 hours to obtain a light yellow solution, dialyzing for 48 hours to remove unreacted silver ions, changing water every 6 hours in the period, and freeze-drying the obtained solution to obtain light yellow particles, namely the high-efficiency antibacterial material AgNPs @ S, N-CQDs composite material.

Referring to FIG. 1, 3000-3500cm can be seen from the infrared absorption curve^-1The wide absorption band is due to the tensile vibration of O-H and N-H, which indicates that the carbon quantum dots S, N-CQDs have many amino and hydroxyl groups on the surface, indicating that the carbon quantum dots S, N-CQDs have high hydrophilicity. 1726cm^-1The absorption of (A) was attributed to C ═ O carbonyl tensile shock, and the decrease in strength demonstrated that there was an interaction between Ag NPs and the oxygen-containing functional group (-COOH) in S, N-CQDs and achieved by formation of a chemical bond or electrostatic attraction, 1380cm^-1The peak at (A) is due to tensile vibration of the sulfide, the Ag NPs @ S, N-CQDs composite set at this point is sharp indicating that the bond in the composite set breaks, in combination with 2286cm, in comparison to the S, N-CQDs sample alone^-1The peak shows that Ag-S bond is generated, Ag NPs is successfully prepared and compounded with carbon quantum dots S, N-CQDs, part of the Ag NPs is wrapped by the S, N-CQDs, and part of the Ag NPs is exposed on the surface to form the Ag NPs @ S, N-CQDs high-efficiency antibacterial composite material.

Referring to fig. 2, according to a TEM image, it can be seen that silver nanoparticles are wrapped between carbon quantum dots S, N-CQDs, the dispersibility is good, the particles are in a sphere-like shape, the particle size is uniform within 10nm, mainly about 5nm, the spacing between the lattice of Ag NPs is marked at the white mark overlapping with the HRTEM image, and the spacing between the lattice of Ag NPs and the (111) plane of Ag is 0.236nm, which indicates that the high-efficiency antibacterial material AgNPs @ S, N-CQDs composite material has been successfully synthesized.

In order to explore the influence of different concentrations of silver nitrate and carbon quantum dots S, N-CQDs reaction ratio on antibacterial performance and the influence of carbon quantum dots containing different miscellaneous elements on antibacterial performance of the silver nanoparticle composite material, the following examples were also carried out and tested:

example 3:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a preparation method thereof, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that: changing different reaction mass ratios of a silver nitrate solution and carbon quantum dot S and N-CQDs solutions, respectively adding the silver nitrate solution and the carbon quantum dot S and the N-CQDs solutions in 5 groups in a mass ratio of 4:1,2:1,1:1,1:2 and 1:4 in a dropwise manner into the carbon quantum dot S and the N-CQDs solutions under the condition of magnetic stirring, continuously stirring for 48 hours to obtain a light yellow solution, dialyzing for 48 hours to remove unreacted silver ions, changing water at intervals of 6 hours, preparing high-efficiency antibacterial materials AgNPs @ S and N-CQDs composite materials with different components, and detecting the Minimum Inhibitory Concentration (MIC).

Comparative example 1:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a comparative example of a preparation method of the high-efficiency antibacterial material, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

preparing N-CQDs containing N hetero-elements by using ethylenediamine and citric acid under a hydrothermal reaction according to the step of example 1; and then mixing the composite material with silver nitrate solution to prepare AgNPs @ CQDs composite materials with different components, performing the process according to the example 2, and performing Minimum Inhibitory Concentration (MIC) detection on the obtained freeze-dried composite material sample.

Comparative example 2:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a comparative example of a preparation method of the high-efficiency antibacterial material, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

CQDs free of hetero elements were prepared according to the procedure of example 1 using citric acid alone under hydrothermal reaction; and then mixing the composite material with silver nitrate solution to prepare AgNPs @ CQDs composite materials with different components, performing the process according to the example 2, and performing Minimum Inhibitory Concentration (MIC) detection on the obtained freeze-dried composite material sample.

The specific process of Minimum Inhibitory Concentration (MIC) assay described in example 3 above, comparative examples 1 and 2 included: bacteria, including Staphylococcus Aureus (SA), methicillin-resistant staphylococcus aureus (MRSA), Escherichia Coli (EC), on solid media were cultured in liquid Luria Broth (LB) media for 18h, Candida Albicans (CA) in saxase liquid media for 24h, before MIC experiments were performed; in a sterilized 96-well plate, 100 μ L LB medium was added to each well, and a carbon quantum dot S, N-CQDs or antimicrobial AgNPs @ S, N-CQDs composite at a certain concentration was added to the first well and serially diluted twice; then 100. mu.L of the solution was added at a concentration of 2X 10⁶CFU/mL of bacterial suspension was added to the wells. The minimum inhibitory concentration MIC is determined by nephelometry, i.e., the concentration of CQDs or AgNPs @ S, N-CQDs composite corresponding to wells without turbidity is the MIC value, as detailed in tables 1 and 2 below:

TABLE 1 MIC values (in mg/mL) for different sets of composites prepared according to different raw material reaction mass ratios

As can be seen from the results of MIC values in Table 1 above, when S, N-CQDs is used in a ratio to AgNO₃When the dosage is more, the antibacterial performance is poorer, the MIC value is gradually reduced along with the increase of the dosage of the silver nitrate, the antibacterial performance is gradually improved, and when AgNO is used₃When the reaction ratio of S to N-CQDs is 1:1, the antibacterial performance is the best, and then the antibacterial performance is increased along with the increase of the dosage of silver nitrateThe change is not too large, and in the experimental process, the phenomenon that when the using amount of silver nitrate is increased, the precipitate is increased and purple, and excessive silver ions are converted into precipitate in the reaction process, so that the antibacterial performance is not improved better.

TABLE 2 MIC values (in mg/mL) for different types of composites prepared using different CQDs

As can be seen from the results of MIC values in Table 2 above, compared with single Ag NPs, the MIC values of AgNPs @ N-CQDs prepared by using N-CQDs and AgNPs @ CQDs prepared by using CQDs containing no hetero elements are higher than those of AgNPs @ S and N-CQDs groups, and the antibacterial properties of the AgNPs @ S and N-CQDs groups are obviously stronger than those of the other two groups, which shows that the AgNPs @ S and N-CQDs have obvious advantages in the antibacterial properties.

Application example 1: after carbon quantum dots S and N-CQDs and high-efficiency antibacterial materials AgNPs @ S and N-CQDs with different concentrations are cultured together with different bacteria, an experimental test of bacteriostasis rate is carried out, and the method specifically comprises the following steps: before carrying out a plate experiment of a bacteriostasis rate test, culturing bacteria on a solid culture medium, including staphylococcus aureus, methicillin-resistant staphylococcus aureus and escherichia coli, in a liquid Luria Broth (LB) culture medium for 18 hours, and culturing candida albicans in a Sasa glucose liquid culture medium for 24 hours; then mixing AgNPs @ S, N-CQDs composite materials or S, N-CQDs with different concentrations with different strains respectively, and keeping the concentration of bacteria in the final system to be 10⁵The concentrations of CFU/mL, AgNPs @ S, N-CQDs composite, S, N-CQDs are 0.03125mg/mL, 0.0625mg/mL, 0.125mg/mL, 0.25mg/mL, 0.5mg/mL, 1mg/mL, 2mg/mL, 4 mg/mL.

And (3) coating the mixed solution of the different samples and the bacteria liquid on an agar plate which is sterilized at high temperature and poured, and culturing for 24 hours in a constant-temperature incubator at 37 ℃, wherein the staphylococcus aureus, the methicillin-resistant staphylococcus aureus and the escherichia coli group are nutrient agar plates, and the candida albicans group is a potato glucose agar plate. Referring to FIG. 3, it can be seen from the plate experiment bacteriostasis rate chart that the two groups of samples all have certain antibacterial ability against gram-positive bacteria, gram-negative bacteria, fungi and antibiotic-resistant bacteria, the high-efficiency antibacterial material AgNPs @ S, the N-CQDs group has more excellent antibacterial performance than the single carbon quantum dots S, N-CQDs on the whole, under the condition of the same concentration, the bacteriostasis rate of the AgNPs @ S, N-CQDs high-efficiency antibacterial composite material group is higher than that of the single carbon quantum dots S, N-CQDs, the antibacterial performance of the composite material against gram-negative bacteria and fungi is stronger than that of gram-positive bacteria, and the high-efficiency antibacterial material AgNPs @ S, N-CQDs composite material also has a very strong antibacterial effect against methicillin-resistant staphylococcus aureus which is a representative strain of antibiotic-resistant bacteria, which shows that the composite material has a very good antibacterial effect on the antibiotic-resistant bacteria.

Example 4:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a preparation method thereof, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

in the preparation process of the carbon quantum dots S, N-CQDs, the mass-volume ratio of citric acid to mercaptoethylamine to deionized water is changed to be 0.4 g: 2 g: 30 mL; the reaction temperature of the hydrothermal reaction is 130 ℃, and the reaction time is 200 min; the dialysis is carried out in a dialysis bag for 36h, and water is changed every 4h in the dialysis process;

in the preparation process of the high-efficiency antibacterial material AgNPs @ S, N-CQDs, the mass volume concentration of an aqueous solution of the carbon quantum dots S, N-CQDs is changed to be 0.5 mg/mL; the mass volume concentration of the silver nitrate aqueous solution is 25 mg/mL.

Example 5:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a preparation method thereof, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

in the preparation process of the carbon quantum dots S, N-CQDs, the mass-volume ratio of citric acid to mercaptoethylamine to deionized water is changed to be 0.8 g: 4 g: 45 mL; the reaction temperature of the hydrothermal reaction is 180 ℃, and the reaction time is 120 min; the dialysis time of the dialysis bag is 72h, and water is changed every 5h in the dialysis process;

in the preparation process of the high-efficiency antibacterial material AgNPs @ S, N-CQDs, the mass volume concentration of an aqueous solution of the carbon quantum dots S, N-CQDs is changed to be 0.5 mg/mL; the mass volume concentration of the silver nitrate aqueous solution is 15 mg/mL.

Example 6:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a preparation method thereof, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

in the preparation process of the carbon quantum dots S, N-CQDs, the mass-volume ratio of citric acid to mercaptoethylamine to deionized water is changed to be 0.54 g: 2 g: 40 ml; the reaction temperature of the hydrothermal reaction is 160 ℃, and the reaction time is 140 min; the dialysis is carried out in a dialysis bag for 48h, and water is changed every 6h in the dialysis process;

in the preparation process of the high-efficiency antibacterial material AgNPs @ S, N-CQDs, the mass volume concentration of an aqueous solution of the carbon quantum dots S, N-CQDs is changed to 1.5 mg/mL; the mass volume concentration of the silver nitrate aqueous solution is 18 mg/mL.

Example 6:

the embodiment provides a carbon quantum dot, a high-efficiency antibacterial material containing nano silver based on the carbon quantum dot and a preparation method thereof, and the specific steps are basically the same as those of the embodiments 1 and 2, and the difference is that:

in the preparation process of the carbon quantum dots S, N-CQDs, the mass-volume ratio of citric acid to mercaptoethylamine to deionized water is changed to be 0.7 g: 3 g: 30 ml; the reaction temperature of the hydrothermal reaction is 140 ℃ and the reaction time is 160 min; the dialysis is carried out in a dialysis bag for 36h, and water is changed every 5h in the dialysis process;

in the preparation process of the high-efficiency antibacterial material AgNPs @ S, N-CQDs, the mass volume concentration of an aqueous solution of the carbon quantum dots S, N-CQDs is changed to be 2 mg/mL; the mass volume concentration of the silver nitrate aqueous solution is 20 mg/mL.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.