Composite polyvinyl alcohol hydrogel with antibacterial function and preparation method thereof

Abstract

The invention provides a composite polyvinyl alcohol hydrogel with an antibacterial function and a preparation method thereof, and particularly relates to a hydrogel with an antibacterial function prepared by doping refined pyroligneous liquor and polyvinyl alcohol with different concentrations and adopting a freeze-thaw method, and the physical and chemical properties of the hydrogel are explored. The RWV / PVA composite hydrogel has the advantages that the antibacterial property of the RWV / PVA composite hydrogel is verified by the aid of staphylococcus aureus and escherichia coli, and the biological safety of the RWV / PVA composite hydrogel is investigated by the aid of cytotoxicity experiments of the hydrogel.

Description

Technical Field

[0001] The present invention relates to the field of water-soluble high molecular polymers, and in particular to a composite polyvinyl alcohol hydrogel with antibacterial function and a preparation method thereof. Background Art

[0002] Microorganisms such as bacteria, fungi, and viruses are ubiquitous in our lives. Because they are difficult to detect with the naked eye and reproduce rapidly, they easily spread a variety of diseases. Bacterial infections, among them, are a potential long-term threat to human health. The use of antibiotics significantly reduced the risk and harm of bacterial infections, but long-term or excessive use has since been shown to lead to antibiotic resistance in bacteria. Therefore, the search for novel antimicrobial strategies and the development of safe and effective antimicrobial materials have become a hot topic of research. Wood vinegar is an acidic, reddish-brown liquid with a distinctive aromatic odor. It has been shown to exhibit excellent antimicrobial and antioxidant activities. As a natural antimicrobial agent, wood vinegar does not cause bacterial resistance, as occurs with antibiotics, nor does it present the biocompatibility issues of metal nanoparticles. During biomass pyrolysis, organic bonds decompose through a series of chemical reactions, including dehydration, hydrolysis, oxidation, decarboxylation, and depolymerization, to produce volatile organic compounds, inorganic gaseous products, water vapor, and tar. The gases are condensed to produce wood vinegar, which contains a high concentration of phenolic compounds, furans, pyridines, ketones, and esters. Refined wood vinegar removes harmful substances and concentrates phenolic compounds, which have excellent antibacterial and antioxidant properties. Studies have shown that wood vinegar has anti-inflammatory and antibacterial properties, making it a potential medical antibacterial agent.

[0003] With advances in medical technology, the development of novel pharmaceutical materials is gaining increasing attention, with wound dressings being a current research hotspot. Hydrogels, due to their excellent flexibility, biocompatibility, and ability to deliver targeted localized medications, are considered promising wound dressing materials. Due to their three-dimensional porous network structure, hydrogels are excellent drug carriers, making them ideal for use as medical antibacterial and anti-inflammatory materials. However, bacterial resistance caused by overuse of antibiotics has become a pressing issue that needs to be addressed.

[0004] Polyvinyl alcohol (PVA) is a water-soluble polymer with advantages such as excellent flexibility, non-toxicity, biodegradability, biocompatibility, ability to degrade in vivo, and no significant irritation to human organs. Therefore, PVA is currently widely used in the pharmaceutical field, mainly including drug delivery vehicles, substrates for drug film-forming agents, medical materials, and pharmaceutical excipients. However, PVA itself does not have antibacterial properties and therefore needs to be loaded with appropriate antimicrobial agents to achieve antibacterial effects. Summary of the Invention

[0005] The present invention aims to provide a composite polyvinyl alcohol hydrogel with antibacterial function, which is suitable for use as a liquid wound dressing.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function comprises the following steps: First, extract the wood vinegar with ethyl acetate, let it stand and separate, collect the organic phase, add sodium bicarbonate solution to the organic phase until no bubbles are generated, let it stand and separate, discard the aqueous phase, extract the organic phase with NaOH solution, add concentrated phosphoric acid to the obtained aqueous phase after sufficient reaction, and finally add disodium hydrogen phosphate solution, extract the organic phase with ethyl acetate, collect the organic phase, and then distill under reduced pressure to obtain refined wood vinegar (RWV); RWV was added to the PVA solution and stirred at room temperature for 2 hours to prepare a hydrogel mixed solution. The mixed solution was then poured into a mold and repeatedly frozen and thawed to form a RWV / PVA composite hydrogel.

[0007] As a more optimal technical solution of the present invention, the method for preparing the PVA solution is as follows: 10 g of PVA solid powder was dissolved in 100 mL of water to prepare a 10 wt % PVA aqueous solution, which was stirred at 80° C. for 5 h until the solution was uniform, and then cooled to normal temperature.

[0008] As a more optimal technical solution of the present invention: the RWV concentration in the hydrogel mixed solution is 1-2.5% (w / w).

[0009] As a more optimal technical solution of the present invention: the number of repeated freezing and thawing is 2-6 times, the conditions are freezing in a refrigerator at -25 to -80°C for 18 hours, and then thawing at room temperature for 6 hours.

[0010] As a more optimal technical solution of the present invention: the number of repeated freezing and thawing is 3 times, the condition is freezing in a refrigerator at -30°C for 18 hours, and then thawing at room temperature for 6 hours.

[0011] As a more optimal technical solution of the present invention: extract the wood vinegar three times with ethyl acetate at a volume ratio of 3:1.

[0012] As a more optimal technical solution of the present invention: the organic phase is extracted three times with a 1 mol / L NaOH solution at a volume ratio of 1:1.

[0013] As a more optimal technical solution of the present invention: the amount of concentrated phosphoric acid added is such that the volume ratio of the organic phase to the concentrated phosphoric acid is 100:1.

[0014] As a more optimal technical solution of the present invention: the mass fraction of the disodium hydrogen phosphate solution is 10%.

[0015] Another object of the present invention is to provide a composite PVA hydrogel with antibacterial function obtained by the above preparation method.

[0016] The beneficial effects are as follows: By exploring the physical and chemical properties of the prepared composite PVA hydrogel with antibacterial function, the present invention concluded that its porous structure is conducive to its drug loading and release as a wound dressing, and the maximum compressive stress reaches 6.81 MPa, taking into account both antibacterial activity and biosafety. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FTIR images of PVA / RWV hydrogels with different concentrations.

[0018] Figure 2 SEM images of PVA / RWV hydrogels with different concentrations.

[0019] Figure 3 Comparison of compressive stress of PVA / RWV hydrogels with different concentrations.

[0020] Figure 4 The graph shows the change of swelling rate of PVA / RWV hydrogel with different concentrations over time.

[0021] Figure 5 A comparison of the porosity of PVA / RWV hydrogels with different concentrations.

[0022] Figure 6 The antioxidant properties of RWV / PVA composite hydrogel.

[0023] Figure 7 The antibacterial properties of RWV / PVA composite hydrogel against Escherichia coli (A) and Staphylococcus aureus (B).

[0024] Figure 8 Effects of different concentrations of RWV / PVA hydrogel on cell activity. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with specific embodiments. The examples given are only for illustrating the present invention, not for limiting the scope of the present invention. The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0026] The materials and reagents used in the following examples are ethyl acetate (AR grade), n-hexane (AR grade), calcium chloride (AR grade), sodium chloride (AR grade), and methanol (AR grade), all of which were purchased from Beijing Chemical Plant. Ziziphus jujuba wood vinegar was purchased from Jilin Musucheng Biotechnology Co., Ltd. Epigallocatechin gallate (EGCG) (biopure) was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. Polyvinyl alcohol 17-99 (AR grade) was purchased from Jiangsu Yatai Chemical Co., Ltd. (Jiangsu, China). Disodium hydrogen phosphate (AR grade), sodium bicarbonate (AR grade), sodium hydroxide (AR grade), and phosphoric acid (AR grade) were all purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). 1,1-Diphenyl-2-picrylhydrazyl (DPPH) (AR grade) was purchased from TCI Chemicals (Shanghai, China). Fetal bovine serum (biopure), DEME medium (biopure) were purchased from Guangzhou Shuopu Biotechnology Co., Ltd., and CCK8 (cell counting kit-8) (AR grade) was purchased from Beyotime Biotechnology Research Institute. LB broth was purchased from Qingdao Haibo Biotechnology Co., Ltd. (Qingdao, China). Nutrient agar was purchased from Hangzhou Baisi Biotechnology Co., Ltd. (Hangzhou, China). SEM model: Hitachi-SU8050 (Japan) The room temperature in the following examples is 23°C.

[0027] Example 1 The method for preparing a composite PVA hydrogel with antibacterial function comprises the following steps: 1. Preparation of RWV.

[0028] First, the wood vinegar is extracted three times with ethyl acetate at a volume ratio of 3:1. After standing and stratifying, the aqueous phase is discarded and the organic phases are combined. A 1 mol / L sodium bicarbonate solution is added to the organic phase until no bubbles are generated. After standing and stratifying, the aqueous phase is discarded, and the organic phases are combined. The organic phase is then extracted three times with a 1 mol / L NaOH solution at a volume ratio of 1:1. After sufficient reaction, the aqueous phase is acidified by adding a certain amount of concentrated phosphoric acid, wherein the volume ratio of the organic phase to the concentrated phosphoric acid is 100:1. Finally, a 10% mass fraction of disodium hydrogen phosphate solution is added, and finally, the organic phase is extracted three times with ethyl acetate at a volume ratio of 1:1. The organic phases are combined. Subsequently, the organic solvent is removed by distillation under reduced pressure to obtain RWV.

[0029] 2. Preparation of RWV / PVA composite hydrogel PVA hydrogel blended with RWV was prepared by freeze-thaw method. 10g PVA solid powder was dissolved in 100mL water to prepare a PVA aqueous solution with a concentration of 10wt%, and stirred at 80℃ for 5h until the solution was uniform. After cooling to normal temperature, different volumes of RWV were added to the prepared PVA solution and stirred at room temperature for 2 hours to prepare a hydrogel mixed solution with a RWV concentration of 2.5% (w / w), named H5. Subsequently, the mixed solution was poured into a mold, frozen in a refrigerator at -30℃ for 18 hours, taken out and thawed at room temperature for 6 hours, and frozen and thawed three times to finally form a RWV / PVA composite hydrogel.

[0030] Example 2 The difference between this embodiment and embodiment 1 is that a hydrogel mixed solution with an RWV concentration of 0% (w / w) is prepared and named H1.

[0031] Example 3 The difference between this embodiment and embodiment 1 is that a hydrogel mixed solution with a RWV concentration of 1% (w / w) is prepared and named H2.

[0032] Example 4 The difference between this embodiment and embodiment 1 is that a hydrogel mixed solution with an RWV concentration of 1.5% (w / w) was prepared and named H3.

[0033] Example 5 The difference between this embodiment and embodiment 1 is that a hydrogel mixed solution with an RWV concentration of 2% (w / w) is prepared and named H4.

[0034] Example 6 The difference between this embodiment and embodiment 1 is that a hydrogel mixed solution with an RWV concentration of 6% (w / w) was prepared and named H6.

[0035] Example 7 The sample was frozen in a -25°C refrigerator for 18 hours and named H7.

[0036] Example 8 The sample was frozen at -80°C for 18 hours and named H8.

[0037] Example 9 The sample was frozen at -50°C for 18 hours and named H9.

[0038] The total phenolic content of wood vinegar and RWV was determined by the folin phenol colorimetric method. The total phenolic content was expressed as (-)-epigallocatechin gallate (EGCG) equivalent, and a standard curve of the linear relationship between EGCG and absorbance (765 nm) was drawn. The specific method was as follows: 0.01 mg / mL, 0.02 mg / mL, 0.03 mg / mL, 0.04 mg / mL, 0.05 mg / mL, 0.06 mg / mL, 0.07 mg / mL, and 0.08 mg / mL EGCG standard solutions were mixed with 1 mol / L folin phenol solution, 7.5% (w / v) Na2CO3 solution, and water, and the mixture was stored in the dark for 30 minutes. The absorbance at 765 nm was measured using a visible spectrophotometer. All experiments were repeated 3 times. The crude wood vinegar and refined wood vinegar were diluted 100-fold and 1000-fold with ethyl acetate, respectively, and then 1 mol / L folin solution, 7.5% (w / v) Na2CO3 solution, and water were added as described above. After storage in the dark for 30 minutes, the absorbance at 765 nm was measured using a visible spectrophotometer. All experiments were repeated three times.

[0039] The standard curve of total phenols measured by EGCG is y=8.662x+0.007, R 2 =0.9992. Calculations based on the standard curve revealed that the total phenol content of crude wood vinegar was 4.834 mg / mL, while that of refined wood vinegar was 165.1 mg / mL. The concentration of phenolic compounds increased approximately 34-fold before and after refining, indicating that this refining method can effectively enhance the functionality of wood vinegar.

[0040] Physical and chemical characterization of RWV / PVA composite hydrogel: Fourier transform infrared (FTIR) spectroscopy; The chemical structure of the RWV / PVA composite hydrogel and the possible interactions between its components were analyzed using a Fourier transform infrared spectrometer (ThermoNicolet360, Thermo Fisher Scientific Inc.) with a scanning range of 4000–400 cm -1 .

[0041] microstructural analysis; The prepared RWV / PVA composite hydrogel was freeze-dried for 48 hours, quenched in liquid nitrogen, and the surface was sprayed with gold. The cross-section of the RWV / PVA composite hydrogel was morphologically characterized using a scanning electron microscope to observe its surface morphology.

[0042] Porosity analysis; The porosity of the RWV / PVA composite hydrogel was investigated using the liquid displacement method. The freeze-dried composite hydrogel sample was weighed (m1) and its volume (V) was measured. The dried sample was then completely immersed in anhydrous ethanol. After standing for 24 hours, the sample was removed from the anhydrous ethanol and weighed (m2). The porosity was calculated using the following formula: ρ is the density of anhydrous ethanol.

[0043] Swelling properties of RWV / PVA composite hydrogel; After freeze-drying, the RWV / PVA composite hydrogel was placed in deionized water at room temperature. The swollen samples were taken out at intervals of 2 h, 4 h, 6 h, 8 h, 10 h, 18 h, and 24 h. The samples were wiped off with filter paper and weighed. The swelling ratio (SR) at each time point can be calculated according to the following formula: Where W0 is the initial mass of the dry sample, and Wt is the mass of the sample after swelling with stream water at each time period.

[0044] Compression performance test; The RWV / PVA composite hydrogel (20 mm in diameter × 20 mm in thickness) was subjected to compression tests using a universal testing machine (5869, Instron, USA). The maximum compression strain was set to 80% and the constant displacement rate was 5 mm / min. The experiments were carried out at room temperature (25°C) and the samples were kept wet during the experiment.

[0045] Antimicrobial activity assay; The antibacterial activity of RWV / PVA composite hydrogel was determined using Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli). First, 10 mL of E.coli and S.aureus bacterial culture fluid was cultured in a bacterial incubator at 37 ° C for 24 hours, and then the bacterial culture fluid was diluted to the concentration to be tested. The RWV / PVA composite hydrogel was divided into discs with a diameter of 1 cm and sterilized under ultraviolet light for 1 hour. The prepared bacterial culture fluid was then evenly spread on the agar medium, and the prepared hydrogel discs were placed on the culture medium and cultured at 37 ° C for 24 hours. As a control, the bacterial culture fluid was cultured under the same conditions. The antibacterial ability of the RWV / PVA hydrogel was determined by measuring the diameter of the inhibition zone. Each group of experiments was repeated 3 times to obtain the average value.

[0046] Antioxidant performance testing; The antioxidant capacity of RWV / PVA composite hydrogel was determined by DPPH free radical scavenging method. First, 0.1 mM DPPH solution was prepared with methanol. After diluting the composite hydrogel sample, 200 μL of the sample was dissolved in 3800 μL DPPH solution. After mixing, the mixture was stored in the dark at room temperature for 30 min. After sufficient reaction, the absorbance was measured at 517 nm using a UV-visible spectrophotometer. The DPPH free radical scavenging activity was calculated using the following formula: Cytotoxicity test; The CCK-8 assay was used to determine cytotoxicity. The RWV / PVA composite hydrogel was formed into small discs and sterilized under UV light for 1 hour. The hydrogel samples were then immersed in cell culture medium at 37°C for 24 hours. HepG2 cells were used to evaluate the cytotoxicity of the RWV / PVA composite hydrogel. 100 μL of HepG2 cell suspension was added to each well of a 96-well plate. The cell suspension was then cultured in a 5% CO2 incubator at 37°C. After cell implantation, 100 μL of the prepared hydrogel sample extract was added to each 96-well plate. Four replicate wells were inoculated at each dilution and cultured for 24 hours. After that, 10 μL of CCK-8 reagent was added. After incubation in the dark for 1 hour, the absorbance at 450 nm was measured. All experiments were repeated three times.

[0047] All experimental data were performed at least three times and are presented as ± SD values. Experimental data with p < 0.05 were considered statistically significant.

[0048] Fourier transform infrared spectroscopy results: RWV / PVA composite hydrogel Figure 1 As shown, the characteristic peaks of PVA appear at 3433 cm -1 The OH stretching vibration at 1383 cm -1 The 1096 cm-1 is caused by the CH-OH bending vibration. -1 At 2925cm -1 and 1633cm -1 The peaks appearing at 3200-3600 cm-1 are attributed to the stretching and bending vibrations of CH. Studies have shown that the -OH stretching vibration in RWV should be located at 3200-3600 cm-1. -1 Within the range, Figure 3 The center is 2928cm -1 The absorption peak at 1632 cm is caused by the stretching of CH in the methyl group, while the absorption peak at 1632 cm -1The absorption peaks at and are caused by aromatic backbone vibrations and C=O stretching. These two characteristic peaks confirm the presence of RWV, but since PVA also exhibits characteristic peaks at these two locations, overlap is possible. In summary, PVA and RWA do not react chemically to produce new chemical substances, indicating that the RWV / PVA composite hydrogel has good chemical compatibility.

[0049] Microscopic morphology results: The scanning electron microscopy results of PVA hydrogels doped with different concentrations of RWV are shown in Figure 2. Figure 2 As shown, the cross-section of the freeze-dried RWV / PVA composite hydrogel exhibits a porous structure. The SEM images show that the addition of different concentrations of RWV significantly affects pore size, with the pores of the hydrogel gradually increasing with the addition of RWV. This is consistent with the experimental results of the composite hydrogel's swelling properties and porosity. The porous structure of the composite hydrogel facilitates drug loading and release in wound dressings.

[0050] Mechanical performance results: The mechanical properties of the composite hydrogel were tested by compression test. Figure 3 As shown in the figure, as the amount of RWV added increases, the compressive stress that the composite hydrogel can withstand increases. When the compressive strain is 50%, the maximum compressive stress that H1 can withstand is 2.89 MPa, while the maximum compressive stress that H5 can withstand reaches 6.81 MPa and H6 is 2.91 MPa. This shows that the addition of a certain amount of RWV improves the mechanical properties of PVA hydrogel. RWV enhances the interaction of hydrogen bonds and makes the physical crosslinking degree of the hydrogel higher. The maximum compressive stress that H7 can withstand is 4.35 MPa, the maximum compressive stress that H8 can withstand is 4.89 MPa, and the maximum compressive stress that H9 can withstand is 3.97 MPa.

[0051] Swelling rate results: As a wound dressing, hydrogel needs to have the function of absorbing tissue fluid or blood, and the swelling property reflects the water absorption capacity of the hydrogel. If the swelling property of the hydrogel is too high, it will cause the hydrogel to deform or even compress the wound tissue, while if the swelling property is too low, it will not be able to absorb body fluid well. Figure 4The results show the swelling properties of RWV / PVA composite hydrogels with different concentrations. The five groups of hydrogels grew rapidly in the first two hours, and after eight hours, they basically reached swelling equilibrium, and the swelling rate increased slowly. At the 24th hour, the swelling rate of H1 was 386.21%, and the swelling rate of H5 was 426.87%. The swelling rate of H6 was 212.35%, the swelling rate of H7 was 300.14%, the swelling rate of H8 was 301.51%, and the swelling rate of H9 was 310.85%. It can be seen that the addition of RWV has a slight effect on the swelling ability of the composite hydrogel. Moreover, the experimental results show that the RWV / PVA hydrogel does not undergo much deformation after swelling, and retains its normal water absorption function. This performance is suitable for its use as a liquid wound dressing.

[0052] Porosity results: The pores of the composite hydrogel of the embodiment are used to absorb liquids such as tissue fluid and can also promote the exchange of substances between cells. Figure 5 As shown, the porosity of H1 is 45.23%, the porosity of H5 is 48.75%, the porosity of H6 is 30.41%, the porosity of H7 is 45.71%, the porosity of H8 is 47.22%, and the porosity of H9 is 46.41%. The experimental results show that the porosity of the composite hydrogel does not change significantly with the addition of RWV, which is consistent with the change in its swelling properties. Hydrogels used as wound dressings in humid environments need to be able to absorb wound exudate to accelerate tissue healing. Experimental results show that the composite hydrogel has the ability to absorb liquid.

[0053] Antioxidant performance results: The antioxidant activity of PVA hydrogels doped with different concentrations of RWV is shown in Figure 2. Figure 6 As shown, the antioxidant activity of H1 was 6.81%, and that of H5 was 84.21%, representing an approximately 13-fold increase in antioxidant activity. The antioxidant activity of the composite hydrogels significantly increased with increasing amounts of RWV. PVA itself does not possess antioxidant activity, suggesting that RWV imparts antioxidant properties to the composite hydrogels. This is related to the high concentration of phenolic compounds such as 2,6-dimethoxyphenol and 2-methoxyphenol contained in RWV. Many inflammatory reactions are caused by pathogens and free radicals, and the excellent antioxidant properties of wood vinegar make it a potent anti-inflammatory. Therefore, hydrogels containing RWV are suitable for use as wound dressings, promoting wound healing and preventing inflammation and infection. The antioxidant activities of H7, H8, and H9 were 49.23%, 60.87%, and 69.56%, respectively.

[0054] Antimicrobial performance results: The experiment selected Staphylococcus aureus and Escherichia coli as representatives of bacteria to evaluate the antibacterial properties of RWV / PVA composite hydrogel. Figure 7 The transparent areas around the hydrogels are all inhibition zones, where no bacteria grow. Therefore, the size of the inhibition zone also represents the antibacterial properties of the RWV / PVA composite hydrogel. Figure 7 No inhibition zone appeared around H1 in A and B, which verified that PVA itself did not have antibacterial activity. As the amount of RWV added increased, the inhibition zone of the composite hydrogel gradually expanded, indicating that the antibacterial ability of the composite hydrogel was positively correlated with the amount of RWV added. When the amount of RWV added reached 2.5%, the diameters of the inhibition zones were 12.58 mm (E. coli) and 10.11 mm (S. aureus), respectively. The addition of RWV significantly improved the antibacterial ability of the PVA hydrogel. Staphylococcus aureus is one of the most common pathogens that cause wound infections. The RWV / PVA composite hydrogel has good antibacterial activity against Staphylococcus aureus, which is conducive to its greater role in wound healing.

[0055] Biocompatibility is the key performance of medical materials to determine whether they can be used as wound dressings. Only materials with low cytotoxicity and high safety can come into contact with the human body. Therefore, testing cytotoxicity is an important indicator to determine whether hydrogels are suitable for wound dressings. Figure 8 As shown, cell viability was measured using the CCK-8 assay. After 24 hours of incubation, cell viability remained above the median lethal dose (IC50), reaching a minimum of 85.54%. At this concentration, the RWV / PVA composite hydrogel demonstrated excellent antimicrobial efficacy. Therefore, the RWV dosage can be appropriately reduced to balance antimicrobial activity and biosafety. These experimental results demonstrate that the biosafety of this composite hydrogel meets the requirements for wound dressings and demonstrates promising application potential.

[0056] The present invention uses a freeze-thaw method to prepare a RWV / PVA composite hydrogel. Analysis of the composite hydrogel's morphological characteristics reveals that the RWV / PVA composite hydrogel possesses a highly porous structure and possesses strong adsorption capacity. The addition of RWV enhances the hydrogel's mechanical, antioxidant, and antibacterial properties. Furthermore, cell viability experiments demonstrate that the RWV / PVA composite hydrogel exhibits certain cytocompatibility. The results suggest that the hydrogel exhibits excellent anti-inflammatory and antibacterial properties, and has promising application prospects as a wound dressing.

Claims

1. A method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function, characterized in that: The steps include: First, extract the wood vinegar with ethyl acetate, let it stand and separate, collect the organic phase, add sodium bicarbonate solution to the organic phase until no bubbles are generated, let it stand and separate, discard the aqueous phase, extract the organic phase with NaOH solution, add concentrated phosphoric acid to the obtained aqueous phase after sufficient reaction, and finally add disodium hydrogen phosphate solution, extract the organic phase with ethyl acetate, collect the organic phase, and then distill under reduced pressure to obtain RWV; RWV was added to the PVA solution and stirred at room temperature for 2 hours to prepare a hydrogel mixed solution. The mixed solution was then poured into a mold and repeatedly frozen and thawed to form a RWV / PVA composite hydrogel.

2. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: Described PVA solution preparation method is as follows: Dissolve 10 g of PVA solid powder in 100 mL of water to prepare a 10 wt% PVA aqueous solution, stir at 80 °C for 5 h until the solution is uniform, and cool to normal temperature.

3. The method for preparing a composite PVA hydrogel with antibacterial function according to claim 1, characterized in that: The RWV concentration in the hydrogel mixed solution is 1-2.5% (w / w).

4. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: The number of repeated freezing and thawing is 2-6 times, and the conditions are freezing in a refrigerator at -25 to -80°C for 18 hours, and then thawing at room temperature for 6 hours.

5. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: The freeze-thaw cycles were performed three times, with the conditions being freezing in a -30°C refrigerator for 18 hours and then thawing at room temperature for 6 hours.

6. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: The wood vinegar was extracted three times with ethyl acetate at a volume ratio of 3:

1.

7. The method for preparing a composite PVA hydrogel with antibacterial function according to claim 1, characterized in that: The organic phase was extracted three times with 1 mol / L NaOH solution at a volume ratio of 1:

1.

8. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: The mass fraction of the disodium hydrogen phosphate solution is 10%.

9. The method for preparing a composite polyvinyl alcohol hydrogel with antibacterial function according to claim 1, characterized in that: The amount of concentrated phosphoric acid added is such that the volume ratio of the organic phase to the concentrated phosphoric acid is 100:

1.

10. A composite polyvinyl alcohol hydrogel with antibacterial function, characterized in that: The composite polyvinyl alcohol hydrogel with antibacterial function is prepared according to the preparation method of claim 1.

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