阅读说明：本技术 一种茶多酚纳米银复合物及其制备方法和用途 (Tea polyphenol nano-silver compound and preparation method and application thereof ) 是由 钟炳伟 郭超 潘泳良 吴舒豪 陈斌超 于 2021-01-08 设计创作，主要内容包括：一种茶多酚纳米银复合物及其制备方法和用途,属于饮用水杀菌技术领域。包括以下步骤：1)称取茶多酚溶于蒸馏水,将乙酸银加入蒸馏水中滴加浓硝酸反应生成混合溶液,在充分搅拌条件下,将混合溶液逐滴加入茶多酚溶液中；2)调节pH值至5-9；3)过夜沉淀,将沉淀真空干燥,即得茶多酚纳米银复合物粉末。上述一种茶多酚纳米银复合物及其制备方法和用途,其制得的茶多酚纳米银复合物具有优良的杀菌效果,抑菌率达到95.54％以上,比等当量的银离子提高了72.30％以上,是等当量茶多酚的7倍以上；微量的茶多酚纳米银复合物就可以起到良好的杀菌作用,既节约了资源,又达到了杀菌的效果,是一种有潜力的纳米复合材料。(A tea polyphenol nano-silver compound and a preparation method and application thereof belong to the technical field of drinking water sterilization. The method comprises the following steps: 1) weighing tea polyphenol, dissolving the tea polyphenol in distilled water, adding silver acetate into the distilled water, dropwise adding concentrated nitric acid to react to generate a mixed solution, and dropwise adding the mixed solution into the tea polyphenol solution under the condition of full stirring; 2) adjusting the pH value to 5-9; 3) and (4) precipitating overnight, and drying the precipitate in vacuum to obtain tea polyphenol nano silver composite powder. According to the tea polyphenol nano-silver compound and the preparation method and the application thereof, the prepared tea polyphenol nano-silver compound has an excellent sterilization effect, the bacteriostasis rate reaches over 95.54 percent, and is improved by over 72.30 percent compared with equivalent silver ions and is over 7 times of equivalent tea polyphenol; the trace tea polyphenol nano-silver compound can play a good role in sterilization, thereby not only saving resources, but also achieving the effect of sterilization, and being a potential nano-composite material.)

1. A tea polyphenol nano-silver compound is characterized in that: the weight ratio of tea polyphenols to silver is 0.8-1.2: 0.1-0.3.

2. The tea polyphenol nano silver complex as claimed in claim 1, wherein the weight ratio of tea polyphenol to silver is 0.9-1.1:0.15-0.25, preferably the weight ratio of tea polyphenol to silver is 1: 0.2.

3. The method for preparing a tea polyphenol nano-silver complex as claimed in claim 1, which comprises the steps of:

1) weighing tea polyphenol, and dissolving in distilled water, wherein the concentration of the tea polyphenol is 5g/L-10 g/L; adding silver acetate into distilled water, dropwise adding concentrated nitric acid into the distilled water, reacting to generate a mixed solution, wherein the silver acetate is 15-30:2-3:5-10 of the concentrated nitric acid and the distilled water, the unit of the silver acetate is mg, the unit of the concentrated nitric acid is D, and the unit of the distilled water is mL; dropwise adding the mixed solution into the tea polyphenol solution under the condition of full stirring, wherein the mixed solution comprises the following components in percentage by weight: the tea polyphenol solution is 5-10:10-20, and the unit is mL;

2) at 23-27 deg.C, with Na₂Adjusting the pH value of the CO3 solution to 5-9 to generate a tan precipitate;

3) and (4) standing overnight for precipitation, placing the mixed solution in a centrifuge for centrifugation, taking the precipitate, removing clear liquid, transferring the precipitate to a watch glass, and performing vacuum drying at 55-65 ℃ to obtain the tea polyphenol nano-silver composite powder.

4. The method for preparing a tea polyphenol nano silver complex as claimed in claim 3, wherein the tea polyphenol in the step 1) is prepared by the following method:

1) drying the tea leaf scraps, then placing the dried tea leaf scraps into a high-speed pulverizer to pulverize, and sieving to obtain green tea powder;

2) according to the solid-liquid ratio of 0-1.2.8: 8-12, adding an alcohol solution into the green tea powder, wherein the concentration of the alcohol is 95%, and placing the mixed solution into a numerical control ultrasonic cleaner for ultrasonic assisted extraction for 5-10 minutes;

3) after extraction, placing the extracting solution in a centrifuge for centrifugation, taking clear liquid and discarding residues;

4) adding ZnCl into the clear liquid₂Performing precipitation reaction, and removing clear liquid to obtain precipitate;

5) adding sulfuric acid into the precipitate obtained in the step 4) to dissolve, precipitating impurities to obtain a transparent orange solution, adding ethyl acetate into the solution to extract to obtain a water layer and an organic layer containing tea polyphenol, and drying the organic layer under the protection of nitrogen to obtain solid tea polyphenol powder.

5. The method for preparing a tea polyphenol nano silver complex as claimed in claim 3, wherein in the step 2): the reaction temperature is 24-26 ℃, and the pH value is adjusted to 6-7.

6. The method for preparing a tea polyphenol nano silver complex as claimed in claim 3, wherein in the step 3): the vacuum drying temperature is 58-62 deg.C, preferably 60 deg.C.

7. The use of the tea polyphenol nano-silver complex as claimed in claim 1 in the preparation of bacteriostatic bactericidal materials.

8. The use of the tea polyphenol nano silver compound as claimed in claim 7 in preparing drinking water for bacteriostasis and sterilization, wherein the concentration of the tea polyphenol nano silver compound in the water solution is 0.8-1.2mg/mL, preferably 1.0 mg/mL.

Technical Field

The invention belongs to the technical field of drinking water sterilization, and particularly relates to a tea polyphenol nano-silver compound and a preparation method and application thereof.

Background

The safety of drinking water has an inseparable relationship with human health, and the drinking water sterilization technology based on the prior conventional drinking water sterilization technology has respective defects. Therefore, the prepared novel antibacterial and bactericidal material has wide development prospect. In the antibacterial field, the research on inorganic nano metal antibacterial agents is always concerned, wherein the nano silver material can well adsorb microorganisms due to the characteristics of high efficiency, heat resistance, strong bactericidal action, large specific surface area and the like, so that a better bactericidal effect is achieved, but the nano silver antibacterial agent also has the defects of high cost, strong photosensitive effect, easiness in oxidative discoloration, easiness in causing heavy metal pollution due to one-time release and the like. Therefore, the finding of a proper organic matter compounded with the nano silver material is a solution for improving the performance of the nano silver material.

In recent years, Tea Polyphenol (TP) has been a research hotspot in food, hygiene, health care and other aspects due to its multiple effects of bacteriostasis, sterilization, anti-tumor, anti-oxidation, immunity improvement and the like. Based on pursuit of people for a high-efficiency and green drinking water disinfection mode, tea polyphenol is expected to be developed into an auxiliary disinfectant of drinking water as a novel plant preparation, and has a very wide application prospect. Although the bactericidal performance of tea polyphenol has broad spectrum, the bactericidal performance of tea polyphenol is not ideal, and dosage is increased or other disinfection modes are combined; in addition, the influence on the water chromaticity caused by the increase of the dosage of the tea polyphenol is a problem to be overcome, and the application and the development of the tea polyphenol in the field of antibacterial disinfection are relatively limited due to the reasons.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to design and provide the technical scheme of the tea polyphenol nano-silver compound, the preparation method and the application thereof, and the trace tea polyphenol nano-silver compound can play a good sterilization role, so that the resource is saved, the sterilization effect is achieved, and the tea polyphenol nano-silver compound is a potential nano-composite material.

The tea polyphenol nano silver compound is characterized in that: the weight ratio of tea polyphenols to silver is 0.8-1.2: 0.1-0.3.

The tea polyphenol nano silver compound is characterized in that the weight ratio of tea polyphenol to silver is 0.9-1.1:0.15-0.25, and the preferred weight ratio of tea polyphenol to silver is 1: 0.2.

The preparation method of the tea polyphenol nano-silver compound is characterized by comprising the following steps:

1) weighing tea polyphenol, and dissolving in distilled water, wherein the concentration of the tea polyphenol is 5g/L-10 g/L; adding silver acetate into distilled water, dropwise adding concentrated nitric acid into the distilled water, reacting to generate a mixed solution, wherein the silver acetate is 15-30:2-3:5-10 of the concentrated nitric acid and the distilled water, the unit of the silver acetate is mg, the unit of the concentrated nitric acid is D, and the unit of the distilled water is mL; dropwise adding the mixed solution into the tea polyphenol solution under the condition of full stirring, wherein the mixed solution comprises the following components in percentage by weight: the tea polyphenol solution is 5-10:10-20, and the unit is mL;

2) at 23-27 deg.C, with Na₂Adjusting the pH value of the CO3 solution to 5-9 to generate a tan precipitate;

3) and (4) standing overnight for precipitation, placing the mixed solution in a centrifuge for centrifugation, taking the precipitate, removing clear liquid, transferring the precipitate to a watch glass, and performing vacuum drying at 55-65 ℃ to obtain the tea polyphenol nano-silver composite powder.

The preparation method of the tea polyphenol nano silver compound is characterized in that the tea polyphenol in the step 1) is prepared by adopting the following method:

1) drying the tea leaf scraps, then placing the dried tea leaf scraps into a high-speed pulverizer to pulverize, and sieving to obtain green tea powder;

2) according to the solid-liquid ratio of 0-1.2.8: 8-12, adding an alcohol solution into the green tea powder, wherein the concentration of the alcohol is 95%, and placing the mixed solution into a numerical control ultrasonic cleaner for ultrasonic assisted extraction for 5-10 minutes;

3) after extraction, placing the extracting solution in a centrifuge for centrifugation, taking clear liquid and discarding residues;

4) adding ZnCl into the clear liquid₂Performing precipitation reaction, and removing clear liquid to obtain precipitate;

5) adding sulfuric acid into the precipitate obtained in the step 4) to dissolve, precipitating impurities to obtain a transparent orange solution, adding ethyl acetate into the solution to extract to obtain a water layer and an organic layer containing tea polyphenol, and drying the organic layer under the protection of nitrogen to obtain solid tea polyphenol powder.

The preparation method of the tea polyphenol nano silver compound is characterized in that in the step 2): the reaction temperature is 24-26 ℃, and the pH value is adjusted to 6-7.

The preparation method of the tea polyphenol nano silver compound is characterized in that in the step 3): the vacuum drying temperature is 58-62 deg.C, preferably 60 deg.C.

The tea polyphenol nano-silver compound is applied to preparing bacteriostatic and bactericidal materials.

The tea polyphenol nano-silver compound has the concentration of 0.8-1.2mg/mL, preferably 1.0mg/mL in the aqueous solution for preparing the drinking water for bacteriostasis and sterilization.

According to the tea polyphenol nano-silver compound and the preparation method and the application thereof, the prepared tea polyphenol nano-silver compound has an excellent sterilization effect, the bacteriostasis rate reaches over 95.54 percent, and is improved by over 72.30 percent compared with equivalent silver ions and is over 7 times of equivalent tea polyphenol. The characterization analysis proves that a plurality of phenolic hydroxyl groups in tea polyphenol molecules can generate complexation with Ag +, so that a good synergistic effect is generated between Ag and tea polyphenol, the bacteriostatic performance of the tea polyphenol is greatly enhanced, and the tea polyphenol has strong reducibility, so that the oxidation of nano silver is effectively avoided, and the bacteriostatic persistence is enhanced. The trace tea polyphenol nano-silver compound can play a good role in sterilization, not only saves resources, but also achieves the effect of sterilization, is a potential nano-composite material, can play a role in the fields of drinking water bacteriostasis and the like in future, and has a great application prospect.

Drawings

FIG. 1 shows UV absorption spectra of tea polyphenol nano-silver complexes with different ratios;

FIG. 2 is a full spectrum analysis of XPS spectra of tea polyphenol nano silver compound with different mixture ratios (a); (b) c1 s; (c) o1 s; (d) ag3 d;

FIG. 3 is XRD spectra of tea polyphenol nano silver compound with different mixture ratios;

FIG. 4 shows the bacteriostatic properties of tea polyphenol nano-silver;

FIG. 5 is a bacteriostatic performance diagram of a tea polyphenol nano-silver complex; the tea polyphenol nano-silver compound with different proportions has bacteriostatic performance; (b) enlarged view of the graph (a) between 0 and 1.0 mg/ml; an experimental graph of the tea polyphenol nano-silver compound with concentration; (d) the tea polyphenol nano-silver minimum bacteriostatic concentration of different proportions;

FIG. 6 is a bactericidal mechanism diagram of tea polyphenol nano silver compound.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

In the tea polyphenol nano silver compound: the weight ratio of tea polyphenols to silver is 1: 0.2.

1) Weighing tea polyphenol, and dissolving in distilled water, wherein the concentration of the tea polyphenol is 5g/L-10 g/L; adding silver acetate into distilled water, dropwise adding concentrated nitric acid into the distilled water, reacting to generate a mixed solution, wherein the silver acetate is 15-30:2-3:5-10 of the concentrated nitric acid and the distilled water, the unit of the silver acetate is mg, the unit of the concentrated nitric acid is D, and the unit of the distilled water is mL; dropwise adding the mixed solution into the tea polyphenol solution under the condition of full stirring, wherein the mixed solution comprises the following components in percentage by weight: the tea polyphenol solution is 5-10:10-20, and the unit is mL;

2) at 23-27 deg.C, with Na₂Adjusting the pH value of the CO3 solution to 5-9 to generate a tan precipitate;

3) and (4) standing overnight for precipitation, placing the mixed solution in a centrifuge for centrifugation, taking the precipitate, removing clear liquid, transferring the precipitate to a watch glass, and performing vacuum drying at the temperature of 60 ℃ to obtain the tea polyphenol nano silver composite powder.

The tea polyphenol is prepared by the following method:

1) drying the tea leaf scraps, then placing the dried tea leaf scraps into a high-speed pulverizer to pulverize, and sieving to obtain green tea powder;

2) according to the solid-liquid ratio of 1: 10, adding an alcohol solution into the green tea powder according to the proportion, wherein the concentration of the alcohol is 95%, and placing the mixed solution into a numerical control ultrasonic cleaner for ultrasonic assisted extraction for 8 minutes;

3) after extraction, placing the extracting solution in a centrifuge for centrifugation, taking clear liquid and discarding residues;

4) adding ZnCl into the clear liquid₂Performing precipitation reaction, and removing clear liquid to obtain precipitate;

5) adding sulfuric acid into the precipitate obtained in the step 4) to dissolve, precipitating impurities to obtain a transparent orange solution, adding ethyl acetate into the solution to extract to obtain a water layer and an organic layer containing tea polyphenol, and drying the organic layer under the protection of nitrogen to obtain solid tea polyphenol powder.

The tea polyphenol nano-silver compound is used for preparing antibacterial materials, particularly drinking water antibacterial agents, and the concentration of the tea polyphenol nano-silver compound in an aqueous solution is 1.0 mg/mL.

In example 1 above, the weight ratio of tea polyphenol to silver is 0.8:0.1, or 0.9:0.15, or 1.1:0.25, or 1.2: 0.3. In the preparation method of the tea polyphenol nano-silver compound, the steps of: step 2) adjusting the pH value to 5, 6, 8 and 9 at 23 ℃, 24 ℃, 26 ℃ or 27 ℃; the vacuum drying temperature in the step 3) is 55 ℃ or 65 ℃. In the preparation method of the tea polyphenol of the invention: step 2), green tea powder: the solid-to-liquid ratio of the alcohol solution is 0.8: 8, or 0.9: 9, or 1.1: 11, or 1.2: 12, ultrasonic treatment time of 5 minutes, 6 minutes, 9 minutes and 10 minutes; in step 2). The technical effects of the present invention can be achieved in the same manner as in embodiment 1.

The beneficial effects of the present invention are further illustrated below in conjunction with the corresponding test data.

Test 1: and (3) a tea polyphenol nano silver antibacterial performance detection test.

Preparing Escherichia coli liquidBulk medium (LB): preparing a culture medium from tryptone, sodium chloride and yeast extract powder in a ratio of 1:1:2, sterilizing at 121 ℃ and subpackaging with glass test tubes, wherein each test tube is filled with 5mL of liquid culture medium. The materials were added to liquid LB at a concentration gradient of 0.1mg/mL, 0.3mg/mL, 0.5mg/mL, 1mg/mL, 1.5mg/mL to 10mg/mL, respectively, and the OD values of the two groups of materials were measured using a UV spectrophotometer. Adding 100 microliter of 10-concentration mixed solution of the group A material and LB⁹The OD value of the CFU/mL Escherichia coli solution was measured. Taking tea polyphenol nano-silver compounds with different proportions, taking pure water as a reference, measuring the OD value of the tea polyphenol nano-silver compounds according to the sequence of adding materials, and finally calculating the bacteriostasis rate according to the measured OD value.

1.1 purity testing of tea polyphenols

And (3) inspecting the purity of the prepared tea polyphenol by a ferrous tartrate colorimetric method, and testing the purity by taking AR-grade tea polyphenol as a standard sample. According to the calculation of the regression equation, the regression equation is finally obtained as follows: and Y is 1.6687X +0.0107, the absorbance value of the prepared tea polyphenol at 0.2mg/mL is measured to be 0.343, and the purity of the prepared tea polyphenol is 99.54% by substituting the value into a linear regression equation.

TABLE 1 absorbance values corresponding to standard solutions of tea polyphenols of different concentrations

1.2 characterization and analysis of tea polyphenol nano-silver complex

FIG. 1 is the ultraviolet absorption spectrum of tea polyphenol nano silver compound with different mixture ratios. As can be seen from fig. 1, as the content of silver is increased, the shape of the ultraviolet absorption spectrum of the composite is changed significantly, the absorption value of the characteristic peak at the wavelength of 324nm is decreased, and the position of the characteristic peak of the measured solution starts to move backward, moving backward from 324nm to 345nm, and finally, stabilizing approximately at the wavelength of 345 nm. This indicates that Ag is accompanied by Ag⁺The tea polyphenol is gradually mixed with Ag⁺A complex reaction occurs to generate a complex with a specific structure, which results in a red shift of the absorption wavelength of the characteristic peak by 21 nm. Because a part of phenolic hydroxyl groups are separated from the metal after the complexation occursThe ions form coordinate bonds, p-pi conjugation formed by lone-pair electrons of phenolic hydroxyl on a benzene ring and a large-pi bond electron system on the benzene ring is enhanced, and an absorption band moves towards a long wavelength direction.

FIG. 2 is an XPS spectrum of tea polyphenol nano-silver complex. The full spectrum analysis chart (2a) shows that in addition to containing C, O two elements, Ag element is also present, which indicates that Ag element is successfully complexed to tea polyphenol. The spectrogram analysis of C1s shows that the three peaks are 288.2eV, 286.5eV and 284.8eV as shown in FIG. 2(b), and the three binding energies are found to correspond to the connection mode of three C atoms of O-C-O, C-OH and C-C respectively and are basically consistent with the molecular configuration of tea polyphenol through searching the standard table of the binding energies of the C atoms. It can be seen that the introduction of Ag does not affect the binding energy of all components in the peak of tea polyphenol C1s, and the differences of C-C bonds forming the main skeleton of tea polyphenol and O-C ═ O on acyl groups in different proportions are not large, thus proving that Ag does not react with the main C skeleton structure of tea polyphenol. And the binding energy of the C atom connected with the phenolic hydroxyl is changed, which proves that the complexation reaction occurs on the phenolic hydroxyl, and the introduction of the new element influences the electron distribution of the C atom. The peaks of the O1s spectrum (FIG. 2c) are represented by 533.9eV, 532.6eV, 531.5eV, which correspond to the connection mode of three O atoms, namely, a pyran epoxy atom, a carboxyl oxygen atom and a phenol oxygen atom, in comparison with the standard table of O atom binding energy. Compared with tea polyphenol nano-silver compounds with different proportions, the energy levels of O atoms in different chemical environments are also shifted, wherein the two peak positions of 533.9eV and 532.6eV respectively correspond to a pyran epoxy atom and a carboxyl oxygen atom, and the binding energy of the two types of O atoms in tea polyphenol in a connection mode is approximately the same. The newly appeared peak position binding energy of the complex is 531.5eV, compared with the phenolic oxygen atom of tea polyphenol, the binding energy at the position is obviously shifted to the high direction, the higher the Ag content is, the more obvious the shift is, because Ag replaces the hydrogen on the original phenolic hydroxyl group, the polarity is larger, so that the electron pair part on the oxygen atom is more inclined to shift to the Ag atom, the negative charge on the O atom is reduced to show the increase of the binding energy, and therefore, the newly appeared peak position binding energy of the complex is corresponding to the Ag-O peak at the position. The spectrogram of Ag3d shows that 368.3eV and 374.3eV have two obvious spectral peaks corresponding to two orbital peaks of Ag3d5/2 and Ag3d3/2 respectively, and surface Ag element exists.

FIG. 3 is XRD spectrum of tea polyphenol nano silver compound with different mixture ratio. As can be seen from the figure, the peaks appear at 38.1 °, 44.4 °, 64.5 ° and 77.3 °, and by comparison with a standard silver card (NBSUS04-0783), the four diffraction peaks are respectively corresponding to the diffraction of the (111), (200), (220) and (311) crystal planes of the cubic phase metallic silver, which indicates that the obtained sample is the pure metallic silver nano-particle with the cubic structure.

And (2) test II: antibacterial performance research experiment of tea polyphenol nano silver compound.

2.1 FIG. 4 shows the bactericidal effect of several bacteriostatic materials with different concentrations on Escherichia coli. The figure shows that the materials have obvious inhibition effect on escherichia coli, the bacteriostasis rate and the concentration are in positive correlation, and the bacteriostasis effect is more obvious along with the increase of the concentration. Under the minimum bacteriostatic concentration, the bacteriostatic rate of the tea polyphenol nano silver compound is improved by 691.74 percent compared with tea polyphenol, is improved by 72.30 percent compared with silver acetate and is improved by 213.10 percent compared with a tea polyphenol copper compound. Under the same concentration, the bacteriostatic rate of the tea polyphenol metal compound is obviously higher than that of the tea polyphenol and tea polyphenol copper compound, and the result shows that the metal is a main factor influencing the bacteriostatic performance, and the bactericidal performance of different types of metal has larger influence on the bactericidal performance of the tea polyphenol compound. Compared with silver acetate, the initial bacteriostasis rate of the tea polyphenol nano-silver compound is slightly less than that of the silver acetate, but the minimum bacteriostasis concentration of the tea polyphenol nano-silver compound is obviously lower than that of the silver acetate, and when the concentration is more than 1.0mg/mL, the influence of the concentration on the bactericidal rate is small, and the bactericidal rate approximately presents a gradual trend along with the change of the concentration of the silver acetate, because the tea polyphenol reacts with the silver to generate an insoluble compound and reduce free-state Ag⁺Concentration in water body, Ag⁺The release mode is non-disposable release, while the release mode of the silver acetate is disposable release, when the concentration is too high, the nano particles can be agglomerated, the specific surface area of the silver is reduced, and the sterilization effect is influenced. In general, compared with other antibacterial materials, the tea polyphenol nano-silver compoundThe antibacterial effect is remarkably improved, and the result is also embodied in other types of tea polyphenol nano metal compounds, because the tea polyphenol nano metal compounds generate a synergistic effect between metal and tea polyphenol to enhance the antibacterial performance of the tea polyphenol nano metal compounds, and the tea polyphenol compounds have strong reducibility, so that the oxidation of the nano metal can be effectively avoided, and the antibacterial persistence is enhanced.

2.2 influence of tea polyphenols and nano-silver complex with different proportions on antibacterial property

From fig. 5, it can be seen that the bacteriostatic effect of the compound in each proportion is not obvious when the concentration is low, and the bacteriostatic effect is increased remarkably after a certain concentration is reached, and then reaches the maximum value. This is because bacteria have a range of tolerance to the environment, free Ag⁺At lower concentrations, the microorganism has the ability to self-regulate itself, but when Ag is in the free state⁺When the concentration exceeds the tolerance upper limit, the survival and propagation of the bacteria can be obviously influenced, and even the bacteria can die. In addition, the bacteriostatic performance of the tea polyphenol nano-silver compounds with different proportions has mutation phenomena, when the mutation concentration is reached, the bacteriostatic rate of the compounds is obviously improved, the bacteriostatic agent seriously damages the growth environment of bacteria, and the bacteria basically cannot survive and reproduce, so the mutation concentration is the minimum bacteriostatic concentration (MIC). The Minimum Inhibitory Concentration (MIC) approximately presents the trend of 'descending first and then ascending', which proves that the inhibitory performance approximately becomes better first and then becomes worse, because the synthesis proportion can change the particle size of the tea polyphenol nano-silver, influence the precipitation equilibrium constant and the surface effect thereof, and further influence the inhibitory effect thereof: when the molar ratio of the silver is lower, the proportion of the silver is lower, the organic ligand fully shields the toxicity of the nano silver, the sterilization principle is similar to that of tea polyphenol, and the sterilization performance is weaker; when the proportion of silver is higher, the nano silver releases free Ag⁺The volume of the agglomerated nano silver is increased under high ionic strength, the effective contact area with bacteria is reduced, the nano characteristics are weakened, and the bacteriostatic effect is reduced.

2.3 tea polyphenols Nano silver sterilizing mechanism

The tea polyphenol and the nano silver have certain bactericidal performance, and the tea polyphenol and the nano silver are complexed to achieve the effect of being specific to the tea polyphenol or the silverThe single use of the disinfectant has better sterilization effect. The action mechanism of the tea polyphenol nano silver compound on escherichia coli is shown in figure 6: after the trace tea polyphenol nano silver is dissolved in water, phenolic hydroxyl and Ag are released⁺In phenolic hydroxyl groups and Ag⁺Under the synergistic effect, the integrity of the cytoplasmic membrane is damaged through a perforation mechanism, small pits are formed on the cell wall, the surface of the cell membrane is also damaged, small holes are formed, and a large amount of reducing sugar, protein and K are generated⁺The leakage from the thallus, the membrane potential and ATP are consumed, and then the active oxygen ions and hydroxyl radicals generated by the tea polyphenol nano-silver compound further oxidize the thallus, so that DNA is concentrated in a tense state in a cell nucleus area and loses the replication capacity, and the thallus is completely killed.

The above test results show that: the tea polyphenol and silver acetate are used as raw materials, a synthesis method based on carrier nanocrystallization is used for preparing the tea polyphenol nano-silver compound, the OD method is used for investigating the antibacterial performance of the tea polyphenol nano-silver with different proportions and different concentrations, the reason that the disinfection effect of the tea polyphenol nano-silver compound is better than that of the tea polyphenol and the silver acetate is determined, the damage sites of escherichia coli are analyzed, and the action mechanism of the compound on the escherichia coli is discussed. Experiments prove that the tea polyphenol nano-silver compound (example 1) has excellent bactericidal effect, and when the ratio of tea polyphenol to silver is 1:0.2, when the concentration is 1.0mg/mL, the sterilization effect is best, the bacteriostasis rate reaches 95.54 percent, is improved by 72.30 percent compared with equivalent silver ions, and reaches 7 times of equivalent tea polyphenol. The technical effects of the invention can also be achieved by carrying out the same tests on other embodiments limited by the invention. The characterization analysis proves that a plurality of phenolic hydroxyl groups in tea polyphenol molecules can generate complexation with Ag +, so that a good synergistic effect is generated between Ag and tea polyphenol, the bacteriostatic performance of the tea polyphenol is greatly enhanced, and the tea polyphenol has strong reducibility, so that the oxidation of nano silver is effectively avoided, and the bacteriostatic persistence is enhanced. The invention researches a tea polyphenol nano-silver disinfectant with excellent effect, a trace amount of tea polyphenol nano-silver compound can play a good role in sterilization, resources are saved, the sterilization effect is achieved, the tea polyphenol nano-silver disinfectant is a potential nano-composite material, can play a role in the fields of drinking water bacteriostasis and the like, and has a great application prospect.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.