CN107325319B

CN107325319B - Preparation method and application of porous polyvinylidene fluoride composite nano-silver film

Info

Publication number: CN107325319B
Application number: CN201710570180.0A
Authority: CN
Inventors: 刘梦龙; 吴军; 罗高兴; 贺伟峰; 邓君; 龚雅利
Original assignee: First Affiliated Hospital of TMMU
Current assignee: First Affiliated Hospital of TMMU
Priority date: 2017-07-13
Filing date: 2017-07-13
Publication date: 2020-07-24
Anticipated expiration: 2037-07-13
Also published as: CN107325319A

Abstract

The invention discloses a preparation method and application of a porous polyvinylidene fluoride composite nano silver film, wherein the preparation method comprises the following steps: 1) preparing a suspension, namely dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and performing magnetic stirring; 2) preparing a membrane casting solution, placing the suspension in a shaking table, and reacting at constant temperature; placing the reacted suspension in a vacuum oven for standing and defoaming; 3) forming a film, namely obtaining a cured film by using a casting solution through an immersion precipitation phase inversion method; 4) cleaning; 5) and (3) drying, namely placing the cleaned cured film in a vacuum oven for drying to obtain the porous polyvinylidene fluoride composite nano silver film. The prepared porous polyvinylidene fluoride composite nano silver film is used for manufacturing artificial skin, has good antibacterial performance and no obvious biotoxicity, and the preparation method has the advantages of simple process, less time consumption and low cost.

Description

Preparation method and application of porous polyvinylidene fluoride composite nano-silver film

Technical Field

The invention relates to the field of application of biological materials, in particular to a preparation method and application of a porous polyvinylidene fluoride composite nano silver film.

Background

The skin is the most important natural barrier of human body, and can protect internal organs and prevent invasion of pathogenic microorganisms and loss of body fluid. Skin wounds caused by wounds, burns, diabetic ulcers and other reasons are extremely easy to be attacked by pathogenic microorganisms in the healing process to cause wound infection and suppuration, so that the wounds are delayed to heal or even not healed. Therefore, an ideal artificial skin should have good antibacterial performance, on one hand, can continuously protect the wound from the invasion of external pathogenic microorganisms, and on the other hand, can kill bacteria which are already planted on the wound to prevent infection from further spreading, and finally, the healing of the wound is promoted and the complete function of the skin is recovered.

The clinically common antibacterial agent is an antibiotic, but in recent years, due to the abuse of the antibiotic, the problem of bacterial drug resistance is increased continuously, and multiple drug-resistant bacteria such as methicillin-resistant staphylococcus aureus, acinetobacter baumannii, pseudomonas aeruginosa and the like are promoted, so that the health of human beings is seriously threatened. Therefore, it is necessary to find antibacterial agents that can replace antibiotics. Research proves that the nano silver is not easily influenced by internal and external factors, and the problem of antibiotic resistance can be well avoided. The nano silver mainly kills bacteria by destroying bacterial cell membranes, DNA and interfering the activity of bacterial respiratory chain enzyme. The particle size is small, the specific surface area is large, and the antibacterial agent has good bactericidal effect on gram-negative bacteria and gram-positive bacteria; meanwhile, the nano silver also has the effects of resisting inflammation, relieving pain and promoting wound healing.

The polyvinylidene fluoride has excellent mechanical property, chemical stability and thermal stability. Meanwhile, the composite is non-toxic, harmless, free of teratogenesis and good in biocompatibility. The polyvinylidene fluoride has low price and is easy to be processed and produced in batches. Therefore, it is an excellent scaffold material for constructing artificial skin.

At present, the chemical reduction method for preparing the nano silver is complex in operation, time-consuming and labor-consuming. In addition, how to effectively compound nano-silver with polyvinylidene fluoride to prepare the antibacterial film also faces certain challenges.

Disclosure of Invention

The invention aims to provide a preparation method and application of a porous polyvinylidene fluoride composite nano silver film, which is simple and easy to operate, and the prepared film has controllable thickness, good biocompatibility and good antibacterial effect.

The preparation method of the porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring for 10-60min at the temperature of 40-80 ℃ and the stirring speed of 1000-1500rpm to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 0.1-1 wt%, and the concentration of the polyvinylidene fluoride in the suspension is 5-20 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting for 12-72 h at the temperature of 25-60 ℃ and at the rotating speed of 50-150 rpm, and standing and defoaming for 1-6 h at the temperature of 30-50 ℃ to obtain a casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 100-1000 microns, and placing the mold containing the casting solution with the thickness of 100-1000 microns into deionized water for standing for 10-60min to obtain a cured film;

4) cleaning: cleaning the cured film obtained in the step 3) with ethanol and deionized water in sequence;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 8-16 h at the temperature of 30-50 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Further, the concentration of silver nitrate in the suspension in the step 1) is 0.425wt%, and the concentration of polyvinylidene fluoride in the suspension in the step 1) is 10 wt%.

Further, in the step 1), magnetic stirring is carried out for 30min under the conditions that the temperature is 60 ℃ and the stirring speed is 1200 rpm.

Further, in the step 2), the reaction is carried out for 24 hours under the conditions of 37 ℃ and 100rpm of rotation speed, and standing and defoaming are carried out for 1 hour under the condition of 40 ℃.

Further, the material of the mold in the step 3) is glass, polytetrafluoroethylene or polyester.

Further, the thickness of the casting solution in the step 3) is controlled to be 500 μm, and then the mold containing the casting solution with the thickness of 500 μm is placed in deionized water and stands for 30min to obtain a cured film.

Further, the drying is carried out for 12 hours at the temperature of 40 ℃ in the step 5).

Use of a porous polyvinylidene fluoride composite nanosilver film in the manufacture of an artificial skin or surgical dressing for the treatment of a skin defect in a human.

Further, the skin defect is a full-thickness defect of skin or a skin infection wound.

The following performance tests were performed on the polyvinylidene fluoride composite nano-silver film of the present invention.

1. And (5) observing by a scanning electron microscope.

Referring to fig. 1, the surface structure of the prepared polyvinylidene fluoride composite nano-silver film was observed under different multiples using a scanning electron microscope. And calculating the aperture of the hole on the surface of the polyvinylidene fluoride composite nano silver film to be 0.5-1.5 mu m by using Image-Pro Plus 6.0 software.

2. And (5) observing by using a transmission electron microscope.

Referring to fig. 2, the morphology and size of nano-silver in the polyvinylidene fluoride composite nano-silver film prepared by transmission electron microscope observation. Observation shows that the nano silver has no agglomeration phenomenon in the polyvinylidene fluoride and is uniformly dispersed; the diameter of the nano silver particles is measured to be 1-5 nm by Image J software.

The invention has the beneficial effects that:

1. the method adopts N, N-dimethylformamide as a dissolving agent and a reducing agent, disperses and dissolves silver nitrate and polyvinylidene fluoride in the N, N-dimethylformamide, and magnetically stirs the mixture at the stirring speed of 1000-1500rpm to generate nano silver in situ in the polyvinylidene fluoride, wherein the diameter of nano silver particles is 1-5 nm; through violent magnetic stirring, the dispersion of the nano-silver in the polyvinylidene fluoride can be realized without adding a pore-foaming agent for ultrasonic dispersion, the agglomeration phenomenon is avoided, and the preparation of the nano-silver and the compounding of the nano-silver and the polyvinylidene fluoride are completed in one step.

2. The invention prepares the porous polyvinylidene fluoride composite nano silver film by an immersion precipitation phase inversion method, instantly performs liquid-liquid phase separation through the interaction of N, N-dimethylformamide and deionized water, finally obtains a characteristic cavity-wrapped structure containing gaps, and prepares the porous polyvinylidene fluoride composite nano silver film with the aperture of 0.5-1.5 mu m, if the aperture is too large, the toughness of the film can be reduced, and the film is easy to be invaded by bacteria, and if the aperture is too small, the air permeability of the film can be reduced, thus influencing the application of the film in artificial skin or surgical dressings.

3. The preparation process of the invention has no waste gas and waste liquid, is environment-friendly, and has simple and easy operation and low cost.

4. The polymer film prepared by the immersion precipitation phase inversion method generally has various structures, and the structure and the performance of the film are greatly influenced by the selection of the polymer, the concentration of the polymer, the selection of a solvent/non-solvent system, the composition of a casting solution and the composition of a gel bath.

Drawings

FIG. 1 is a scanning electron microscope photograph of polyvinylidene fluoride composite nano-silver film prepared by the present invention under different times;

FIG. 2 is a transmission electron microscope photograph of a polyvinylidene fluoride composite nano-silver film prepared by the present invention;

FIG. 3 is a histogram comparing the cell activity of the prepared porous PVDF nano-silver film;

FIG. 4 is a histogram of absorbance contrast of an antibacterial property detection experiment of the prepared porous polyvinylidene fluoride composite nano-silver film;

FIG. 5 is a bar graph comparing the wound healing rate of animal experiments of the prepared porous polyvinylidene fluoride composite nano-silver film;

fig. 6 is a bar graph comparing wound healing time of animal experiments of the prepared porous polyvinylidene fluoride composite nano silver film.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The first embodiment is as follows: a preparation method of a porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring for 30min at the temperature of 60 ℃ and the stirring speed of 1200rpm to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 0.425wt%, and the concentration of the polyvinylidene fluoride in the suspension is 10 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting for 24 hours at the temperature of 37 ℃ and the rotating speed of 100rpm, and standing and defoaming for 1 hour at the temperature of 40 ℃ to obtain a casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 500 microns, and placing the mold containing the casting solution with the thickness of 500 microns into deionized water for standing for 30min to obtain a cured film;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 12 hours at the temperature of 40 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Example two: a preparation method of a porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring for 10min at 40 ℃ and at the stirring speed of 1000rpm to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 0.1wt%, and the concentration of the polyvinylidene fluoride in the suspension is 5 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting at a constant temperature of 25 ℃ and a rotation speed of 50rpm for 12 hours, and standing and defoaming at a temperature of 30 ℃ for 1 hour to obtain a membrane casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 100 microns, and placing the mold containing the casting solution with the thickness of 100 microns into deionized water for standing for 10min to obtain a cured film;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 8 hours at the temperature of 30 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Example three: a preparation method of a porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring at 80 ℃ and 1500rpm for 60min to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 1wt%, and the concentration of the polyvinylidene fluoride is 20 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting at a constant temperature of 30 ℃ and a rotation speed of 150rpm for 72h, and standing and defoaming at a temperature of 50 ℃ for 6h to obtain a membrane casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 1000 microns, and placing the mold containing the casting solution with the thickness of 1000 microns into deionized water for standing for 60min to obtain a cured film;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 16 hours at the temperature of 50 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Example four: a preparation method of a porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring at 50 ℃ and at a stirring speed of 1100rpm for 20min to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 0.2wt%, and the concentration of the polyvinylidene fluoride in the suspension is 7 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting at a constant temperature of 45 ℃ and a rotation speed of 70rpm for 48 hours, and standing and defoaming at a temperature of 35 ℃ for 2 hours to obtain a membrane casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 300 microns, and placing the mold containing the casting solution with the thickness of 300 microns into deionized water for standing for 40min to obtain a cured film;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 10 hours at the temperature of 35 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Example five: a preparation method of a porous polyvinylidene fluoride composite nano silver film comprises the following steps:

1) preparation of a suspension: dispersing and dissolving silver nitrate in N, N-dimethylformamide, adding polyvinylidene fluoride, and magnetically stirring for 40min at the temperature of 70 ℃ and the stirring speed of 1400rpm to obtain a suspension, wherein the concentration of the silver nitrate in the suspension is 0.7wt%, and the concentration of the polyvinylidene fluoride in the suspension is 15 wt%;

2) preparing a casting solution: placing the suspension obtained in the step 1) in a shaking table, reacting for 36h at a constant temperature of 50 ℃ and a rotation speed of 120rpm, and standing and defoaming for 4h at a temperature of 45 ℃ to obtain a membrane casting solution;

3) film forming: pouring the casting solution obtained in the step 2) into a mold, controlling the thickness of the casting solution to be 700 mu m, and placing the mold containing the casting solution with the thickness of 700 mu m into deionized water for standing for 50min to obtain a cured film;

5) and (3) drying: and (3) placing the cured film cleaned in the step 4) in a vacuum oven, and drying for 14 hours at the temperature of 45 ℃ to obtain the porous polyvinylidene fluoride composite nano silver film, wherein the aperture of the film is 0.5-2.5 mu m.

Example six: in order to examine the cell activity of the prepared porous polyvinylidene fluoride composite nano-silver film for artificial skin, the following experiment was performed.

1) Cutting the sample prepared in the first embodiment into a film sheet with the size of 1 × 1cm, soaking the film sheet in 75% ethanol solution for disinfection for 30min, and then rinsing the film sheet for 3 times by using phosphate buffer solution;

2) adding 1m L culture solution 1640 containing 10% fetal calf serum into the membrane sheet treated in the step 1), and leaching at 37 deg.C for 24h to obtain leaching solution;

3) inoculating a human epidermal cell line HaCaT cell in a logarithmic growth phase to a 96-well plate at a density of 3000 cells/well for culture, and removing an original culture medium after the cell grows in an adherent manner for 24 hours;

4) grouping experiments:

an experimental group, namely adding the leaching solution prepared in the step 2) into the HaCaT cells cultured in the step 3) according to 100 mu L per hole;

control group: adding an equal amount of 1640 medium containing 10% fetal bovine serum to the HaCaT cells cultured in the step 3); the experimental group and the control group are planted in 4 wells;

blank group: cell-free, only add 1640 medium containing 10% fetal bovine serum;

5) culturing for three days, carrying out cell proliferation detection experiments every day, discarding the original leaching liquor or culture medium, washing the cells of an experimental group and a control group twice by using a phosphate buffer solution, adding 100 mu L of a new culture medium and 10 mu L of a CCK8 reagent into each hole, wherein the CCK8 reagent is purchased from Shanghai Biyun Tian company, incubating for 2 hours at 37 ℃, detecting the absorbance of each hole at the wavelength of 450nm by using an enzyme labeling instrument, calculating the cell activity of the experimental group, and drawing a bar chart according to the calculation formula of (absorbance of the experimental group-blank group)/(absorbance of the control group-blank group) × 100%.

As a result: referring to fig. 3, on the first day, the second day and the third day after inoculation, the cell activities of the experimental groups are all over 95%, and have no obvious difference compared with the cell activities of the control group, which indicates that the prepared porous polyvinylidene fluoride composite nano-silver film has no obvious cytotoxicity and higher safety.

Example seven: in order to test the antibacterial activity of the prepared porous polyvinylidene fluoride composite nano-silver film for artificial skin on drug-resistant bacteria, the following experiments are carried out:

1) the experimental groups comprise an experimental group, a control group, a blank group and no reagent, wherein the experimental group comprises the porous polyvinylidene fluoride composite nano silver film prepared in the first embodiment, the control group comprises streptomycin with the concentration of 1mg/M L, tetracycline with the concentration of 10 mu M, ceftazidime with the concentration of 10 mu M, and the blank group is not added.

2) Cutting the sample prepared in the first embodiment into a film sheet with the size of 1 × 1cm, soaking the film sheet in 75% ethanol solution for disinfection for 30min, and then rinsing the film sheet for 3 times by using phosphate buffer solution;

3) taking multiple drug-resistant acinetobacter baumannii in logarithmic growth phase, wherein the multiple drug-resistant acinetobacter baumannii is provided by a microbiological laboratory of the department of burn in southwest hospital in the third military medical science and university, diluting the multiple drug-resistant acinetobacter baumannii with L B culture medium to a bacterial liquid with an enzyme-labeling instrument with the detection absorbance of 0.07 at the wavelength of 600nm, and adding the diluted bacterial liquid into a 24-pore plate according to 500 mu L per pore;

4) respectively adding the thin film tablet prepared in the step 2), streptomycin with the concentration of 1mg/M L, tetracycline with the concentration of 10 mu M and ceftazidime with the concentration of 10 mu M into each pore bacterial solution of a 24-pore plate, and then placing the 24-pore plate in a shaking table with the temperature of 37 ℃ and the rotating speed of 50rpm for reaction for 24 hours;

5) collecting 24-well plates, sucking 100 mu L bacterial liquid into 96-well plates per well, detecting and recording absorbance values at 600nm wavelength by using a microplate reader, and drawing a histogram.

As a result: referring to fig. 4, the absorbance values of the experimental group are obviously lower than those of the blank group and the control group, which suggests that the porous polyvinylidene fluoride composite nano silver film can obviously inhibit the growth of acinetobacter baumannii, and the effect is obviously better than that of antibiotics, so that the porous polyvinylidene fluoride composite nano silver film can effectively inhibit the growth of drug-resistant bacteria, and has good antibacterial effect.

Example eight: in order to examine the effects of the prepared porous polyvinylidene fluoride composite nano silver film for artificial skin on the inhibition of in vivo bacterial infection and the healing of wound surfaces, the following experiments are carried out:

1) a BA L B/C mouse (purchased from the center of laboratory animals of the third department of medical university) full-thickness skin defect wound model is prepared by carrying out 1% pentobarbital sodium intraperitoneal injection (100mg/kg, 0.01ml/g) on the mouse, fixing the mouse in a prone position, preparing skin in a back operation area, disinfecting the operation area by using a 75% ethanol cotton ball, respectively forming full-thickness skin defect wounds with the diameter of 6mm on both sides of the back by using a puncher, immediately photographing and recording the wounds, and taking the wound area as the initial wound area.

2) Sample coating preparation, cutting the porous polyvinylidene fluoride composite nano silver film prepared in the first embodiment and Vaseline gauze into a size of 0.8 × 0.8.8 cm, sterilizing the front and back surfaces of the film for 30min by ultraviolet rays, taking Acinetobacter baumannii liquid diluted by 10 mu L into 0.5 standard McLee units, coating the Acinetobacter baumannii liquid on the surface of a sample, and naturally drying the sample for 10min for later use.

3) Experimental groups: coating a bacterial surface on the porous polyvinylidene fluoride composite nano-silver film to cover the wound surface, and fixing the wound surface by using a negative pressure suction film; control group: coating vaseline gauze on the surface of the wound to cover the wound, and fixing the vaseline gauze by using a negative pressure suction film; blank group: the wound surface is attached only by a negative pressure suction film. 30 mice were taken and 10 mice were randomly assigned to each group for the experiment.

4) 5 mice were taken from the three groups on days 3 and 7 after surgery, wound surface photographing records were opened, and wound surface healing conditions were observed. Mice were sacrificed by cervical dislocation after day 7. The fixed negative pressure suction membrane of the remaining 15 mice (5 mice each group) was removed on the eighth day, the wound surface was observed every day, the complete healing of the wound surface was obtained when the wound surface had become completely epithelialized, and the time required for complete healing of the wound surface was recorded.

5) Analyzing the group wound surface pictures of the 3 rd day and the 7 th day by using Image Pro Plus 6.0 software, measuring the residual wound surface area, namely the area surrounded by the wound margin, and calculating the wound surface healing rate according to the following formula:

wound healing rate = (initial wound area-remaining wound area)/initial wound area × 100%;

6) and respectively carrying out statistical analysis on the healing rates of the three groups of wound surfaces on the 3 rd day and the 7 th day and the time required for complete healing of the wound surfaces by adopting a one-factor variance analysis method.

As a result: the wound surface covered by the porous polyvinylidene fluoride composite nano silver film has no red swelling and pus exudation on the 3 rd day and the 7 th day, and is consistent with the blank group, while the wound surface of the vaseline gauze group has a large amount of pus exudation and red swelling of wound edge. Referring to fig. 5, the comparison results of the wound healing rates at various time points show that the porous polyvinylidene fluoride composite nano silver film is obviously higher than a vaseline gauze group, and has no significant difference with a blank group without bacterial infection, which suggests that the porous polyvinylidene fluoride composite nano silver film can effectively prevent invasion and infection of drug-resistant acinetobacter baumannii and maintain a normal healing microenvironment of the wound. Referring to fig. 6, the results of comparing the wound healing time show that: the healing time of the porous polyvinylidene fluoride composite nano silver film group is obviously shortened compared with that of a vaseline gauze group, and the porous polyvinylidene fluoride composite nano silver film is prompted to prevent the adverse effect of bacterial infection on wound healing.

The foregoing lists merely illustrate specific embodiments of the invention. It is obvious that the invention is not limited to the above-described embodiments, but that many combinations of operations are possible. All matters hithertofore set forth or suggested by those skilled in the art, including the description herein, are to be understood as being within the scope of the invention.

Claims

1. A preparation method of a porous polyvinylidene fluoride composite nano silver film is characterized by comprising the following steps:

2. The preparation method of the porous polyvinylidene fluoride composite nano-silver film according to claim 1, characterized by comprising the following steps: in the step 1), the concentration of silver nitrate in the suspension is 0.425wt%, and the concentration of polyvinylidene fluoride is 10 wt%.

3. The method for preparing a porous polyvinylidene fluoride composite nano-silver film according to claim 1 or 2, characterized in that: the magnetic stirring is carried out for 30min under the conditions that the temperature is 60 ℃ and the stirring speed is 1200rpm in the step 1).

4. The method for preparing a porous polyvinylidene fluoride composite nano-silver film according to claim 1 or 2, characterized in that: in the step 2), the reaction is carried out for 24 hours under the conditions of 37 ℃ and 100rpm of rotating speed, and the mixture is kept stand and defoamed for 1 hour under the condition of 40 ℃.

5. The method for preparing a porous polyvinylidene fluoride composite nano-silver film according to claim 1 or 2, characterized in that: the material of the mould in the step 3) is glass, polytetrafluoroethylene or polyester.

6. The method for preparing a porous polyvinylidene fluoride composite nano-silver film according to claim 1 or 2, characterized in that: and 3), controlling the thickness of the casting solution to be 500 micrometers in the step 3), and then placing the mold containing the casting solution with the thickness of 500 micrometers in deionized water for standing for 30min to obtain a cured film.

7. The method for preparing a porous polyvinylidene fluoride composite nano-silver film according to claim 1 or 2, characterized in that: the drying is carried out for 12h at the temperature of 40 ℃ in the step 5).

8. Use of a porous polyvinylidene fluoride composite nanosilver film prepared by the method of any one of claims 1 to 7 in the preparation of an artificial skin or surgical dressing for the treatment of skin defects in humans.

9. The use of claim 8, wherein the skin defect is a full-thickness defect of skin or a skin infected wound.