A double-layer sustained-release antibacterial piezoelectric composite membrane, its preparation method and application

Abstract

The present invention discloses a double-layer sustained-release antibacterial piezoelectric composite film and its preparation method and application, belonging to the technical field of biomedical materials. The double-layer sustained-release antibacterial piezoelectric composite film comprises a piezoelectric film and a sustained-release film, and the piezoelectric film and the sustained-release film are encapsulated to obtain the double-layer sustained-release antibacterial piezoelectric composite film; wherein, the piezoelectric film comprises poly(L-lactic acid), nano-zinc oxide and riboflavin; the sustained-release film comprises a polymer layer and an antibacterial drug layer, and the antibacterial drug layer is coated on the surface of the polymer layer. The double-layer sustained-release antibacterial piezoelectric composite film in the present invention has good sustained-release characteristics, antibacterial property, piezoelectric property and biocompatibility, and can promote angiogenesis, wound healing and reduce inflammatory reactions. In addition, the raw materials in the present invention have good biocompatibility, wide sources, low prices and are easy to obtain, and the preparation process is simple. Therefore, it has good application prospects in the preparation of medical wound repair materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and particularly relates to a double-layer sustained-release antibacterial piezoelectric composite film, a preparation method thereof, and an application thereof. Background Art

[0002] The skin is the largest organ of the human body, which can play a role in protecting the human body. Once the skin is damaged, a large number of bacteria will enter the human body, causing wound infections. Multiple factors such as bacterial infection, excessive accumulation of wound exudates, poor local perfusion, and insufficient cell recruitment often delay the healing process of infected skin lesions. Therefore, how to antibacterial and promote the rapid healing of damaged skin surfaces and develop new medical dressings is of great significance for protecting the human immune system.

[0003] Research shows that electrical stimulation has multiple functions such as antibacterial, guiding cell migration, and proliferation during the wound healing process. Its integration with medical dressings has brought new opportunities for the application of electrical stimulation in the field of wound repair. At the same time, giving certain drug stimulation to the wound can regulate cell growth factors, enhance cell vitality, and promote wound repair and tissue regeneration. However, direct drug application to the wound requires high doses and frequent administrations to achieve ideal therapeutic effects.

[0004] Therefore, the current medical dressings still have problems such as insufficient piezoelectric performance, the need for high doses and frequent administrations, resulting in drug waste and low utilization rates. Summary of the Invention

[0005] The purpose of the present invention is to provide a double-layer sustained-release antibacterial piezoelectric composite film, a preparation method thereof, and an application thereof, which are used to solve the problems that the existing medical dressings still have insufficient piezoelectric performance, the need for high doses and frequent administrations, resulting in drug waste and low utilization rates.

[0006] In the first aspect, the present invention provides a double-layer sustained-release antibacterial piezoelectric composite film, including a piezoelectric film and a sustained-release film. The piezoelectric film and the sustained-release film are encapsulated to obtain the double-layer sustained-release antibacterial piezoelectric composite film; wherein, the piezoelectric film includes poly(L-lactic acid), zinc oxide nanoparticles, and riboflavin; the sustained-release film includes a polymer layer and an antibacterial drug layer, and the antibacterial drug layer is coated on the surface of the polymer layer.

[0007] In the present invention, using poly(L-lactic acid), zinc oxide nanoparticles, and riboflavin as raw materials, a piezoelectric film with better piezoelectric performance is prepared. Further, the piezoelectric film and the sustained-release film are encapsulated to obtain a composite film; the composite film has good sustained-release characteristics, antibacterial properties, piezoelectric properties, and biocompatibility, and can promote angiogenesis, wound healing, and reduce inflammatory reactions.

[0008] In some embodiments, the content of L-polylactic acid is 8-15% by mass percentage, for example, it can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or other values within this range; the content of the high molecular polymer layer is 10-20%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20% or other values within this range; and in the piezoelectric film, the mass ratio of L-polylactic acid, nano-zinc oxide and riboflavin is 1:(0.02-1):(0.1-0.5), for example, it can be 1:0.02:0.1, 1:0.02:0.3, 1:0.02:0.5, 1:0.5:0.1, 1:0.5:0.3, 1:0.5:0.5, 1:1:0.1, 1:1:0.3, 1:1:0.5 or other values within this range.

[0009] In the present invention, the inventors have found through research that in the chiral molecule L-polylactic acid, the -CO-O polar group is connected to an asymmetric carbon atom and is oriented in a helical conformation; when the helix is sheared through its side chain, a slight rotation of the C=O dipole will cause a change in molecular polarization, and its direction is perpendicular to the plane of the applied stress; therefore, due to the rotation sum of all C=O dipoles branched from the main chain, electrode polarization occurs. When riboflavin is added to the piezoelectric film, the crystallinity and molecular orientation of L-polylactic acid can be enhanced to obtain a higher piezoelectric output; at the same time, the mixture of L-polylactic acid and riboflavin composed of hydroxyl, carbonyl and amino groups has low cytotoxicity. In addition, when nano-zinc oxide with piezoelectric properties is added to the piezoelectric film, nano-zinc oxide and riboflavin can significantly improve the piezoelectricity of L-polylactic acid, and the three work synergistically to make the piezoelectric film have higher piezoelectricity.

[0010] In some embodiments, the high molecular polymer layer includes polyethersulfone and polyvinylpyrrolidone, and the mass ratio of polyethersulfone to polyvinylpyrrolidone is 1:(0.2-0.5), for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5 or other values within this range.

[0011] In some embodiments, the antibacterial drug layer includes poly(lactic-co-glycolic acid) and levofloxacin, and the mass ratio of poly(lactic-co-glycolic acid) to levofloxacin is 1:(0.05-0.15), for example, it can be 1:0.05, 1:0.07, 1:0.09, 1:0.11, 1:0.13, 1:0.15 or other values within this range; and the content of levofloxacin on the surface of the high molecular polymer layer is 0.005-0.01 mg / cm 2 , for example, it can be 0.005 mg / cm 2 , 0.006 mg / cm 2 , 0.007 mg / cm 2, 0.008 mg / cm 2 , 0.009 mg / cm 2 , 0.01 mg / cm 2 or other values within this range.

[0012] In some embodiments, the purity of the L-polylactic acid is 90-99%, for example, it can be 90%, 92%, 94%, 96%, 98%, 99% or other values within this range; the molecular weight is 20,000-24,000, for example, it can be 20,000, 21,000, 22,000, 23,000, 24,000 or other values within this range; the purity of riboflavin is 90-99%, for example, it can be 90%, 92%, 94%, 96%, 98%, 99% or other values within this range; the purity of polyethersulfone is 90-99%, for example, it can be 90%, 92%, 94%, 96%, 98%, 99% or other values within this range.

[0013] In a second aspect, the present invention provides a method for preparing any of the above double-layer sustained-release antibacterial piezoelectric composite membranes, comprising the following steps: adding L-polylactic acid, nano-zinc oxide and riboflavin into an organic solution and stirring to dissolve to obtain a spinning solution, performing electrospinning on the spinning solution, and drying to obtain a piezoelectric membrane; adding polyethersulfone and polyvinylpyrrolidone into an organic solution and stirring to dissolve to obtain a spinning solution, performing electrospinning on the spinning solution, and drying to obtain a polymer layer; adding polylactic acid-glycolic acid and levofloxacin into an organic solution and stirring to dissolve to obtain a precursor solution, and then coating the precursor solution on the surface of the polymer layer to obtain a sustained-release membrane; encapsulating the piezoelectric membrane and the sustained-release membrane to obtain a double-layer sustained-release antibacterial piezoelectric composite membrane.

[0014] In some embodiments, during the preparation of the double-layer sustained-release antibacterial piezoelectric composite membrane, after the piezoelectric membrane and the sustained-release membrane are encapsulated, the surface of the polymer layer coated with the precursor solution is away from the piezoelectric membrane.

[0015] In some embodiments, during the preparation of the double-layer sustained-release antibacterial piezoelectric composite membrane, the encapsulation can be carried out by conventional methods in the art, for example, kapton tape can be used for encapsulation.

[0016] In some embodiments, during the preparation of the piezoelectric film, the organic solution includes dichloromethane and N,N-dimethylformamide. The stirring and dissolution include: the stirring and dissolution time is 6 to 12 h, for example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or other values within this range; the drying includes: the drying temperature is 30 to 45 °C, for example, it can be 30 °C, 32 °C, 34 °C, 37 °C, 40 °C, 42 °C, 45 °C or other values within this range; the time is 12 to 24 h, for example, it can be 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or other values within this range.

[0017] In some embodiments, during the preparation of the polymer layer, the organic solution includes N,N-dimethylformamide. The stirring and dissolution include: the stirring and dissolution time is 6 to 12 h, for example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or other values within this range; the drying includes: the drying temperature is 30 to 45 °C, for example, it can be 30 °C, 32 °C, 34 °C, 37 °C, 40 °C, 42 °C, 45 °C or other values within this range; the time is 12 to 24 h, for example, it can be 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or other values within this range.

[0018] In some embodiments, during the preparation of the sustained-release film, the organic solution includes N,N-dimethylformamide. The stirring and dissolution include: the stirring and dissolution time is 6 to 12 h, for example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or other values within this range; the coating includes: electrostatic spraying is used for spraying; the drying includes: the drying temperature is 30 to 45 °C, for example, it can be 30 °C, 32 °C, 34 °C, 37 °C, 40 °C, 42 °C, 45 °C or other values within this range; the time is 12 to 24 h, for example, it can be 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or other values within this range.

[0019] In the present invention, the antibacterial drug layer is sprayed on the surface of the polymer layer by electrostatic spraying to obtain a sustained-release film, which can significantly improve the dispersibility and stability of the drug, prolong the action time of the drug, and reduce the toxic and side effects.

[0020] It should be noted that the coating in the present invention can be carried out by conventional methods in the art, and electrostatic spraying is preferably used for spraying.

[0021] In a third aspect, the present invention provides the application of any of the above double-layer sustained-release antibacterial piezoelectric composite films in the preparation of medical wound repair materials.

[0022] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention uses L-polylactic acid, nano zinc oxide and riboflavin as raw materials to prepare a piezoelectric film with good piezoelectric performance, and further encapsulates the piezoelectric film and the sustained-release film to obtain a composite film; the composite film has good sustained-release properties, antibacterial properties, piezoelectricity and biocompatibility, and can promote angiogenesis, wound healing and reduce inflammatory response. In addition, the raw materials in the present invention have good biocompatibility, wide sources, low prices, easy to obtain, and simple preparation process, therefore, it has good application prospects in the preparation of medical wound repair materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a result diagram of the swelling rate of the double-layer sustained-release antibacterial piezoelectric composite film prepared in Example 2 of the present invention;

[0024] Figure 2 This is a graph showing the output voltage results of the piezoelectric film prepared in Comparative Example 1 of the present invention;

[0025] Figure 3 This is a graph showing the output voltage results of the piezoelectric film prepared in Example 1 of the present invention;

[0026] Figure 4 This is a graph showing the output voltage results of the piezoelectric film prepared in Example 2 of the present invention;

[0027] Figure 5 This is a graph showing the output voltage results of the piezoelectric film prepared in Example 3 of the present invention;

[0028] Figure 6 This is a graph showing the antibacterial (Escherichia coli) performance test results of the double-layer sustained-release antibacterial piezoelectric composite film prepared in Example 2 of the present invention and the high molecular polymer layer prepared in Comparative Example 2;

[0029] Figure 7 This is a graph showing the antibacterial (Staphylococcus aureus) performance test results of the double-layer sustained-release antibacterial piezoelectric composite film prepared in Example 2 of the present invention and the high molecular polymer layer prepared in Comparative Example 2;

[0030] Figure 8 This is a graph showing the cytotoxicity test results of the double-layer sustained-release antibacterial piezoelectric composite film prepared in Example 2 of the present invention and the piezoelectric films prepared in Comparative Examples 1 and 3. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] For the experimental methods without specific conditions noted in the examples, they are generally carried out according to the conventional conditions and the conditions described in the manual, or according to the conditions recommended by the manufacturer. For the general equipment, materials, reagents, etc., if there is no special description, they can all be obtained commercially.

[0033] Example 1

[0034] A preparation method of a double-layer sustained-release antibacterial piezoelectric composite film, comprising the following steps:

[0035] S1. Dissolve 500 mg of L-polylactic acid (purity 95%, molecular weight 22000) in 2 ml of dichloromethane (purity 95%), stir evenly, then add 3 ml of N,N-dimethylformamide (purity 95%), and finally add 25 mg of nano-zinc oxide and 75 mg of riboflavin (purity 95%), stir and dissolve for 10 h to obtain a spinning solution. Perform electrospinning on the spinning solution and dry it at 37 °C for 18 h to obtain a piezoelectric film;

[0036] S2. Add 750 mg of polyethersulfone (purity 95%) and 290 mg of polyvinylpyrrolidone to 5 ml of N,N-dimethylformamide, stir and dissolve for 12 h to obtain a spinning solution. Perform electrospinning on the spinning solution and dry it at 37 °C for 18 h to obtain a polymer layer;

[0037] S3. Add 100 mg of poly(lactic-co-glycolic acid) and 10 mg of levofloxacin to 5 ml of N,N-dimethylformamide, stir and dissolve for 12 h to obtain a precursor solution, and then spray the precursor solution on the surface of the polymer layer by electrospray to obtain a sustained-release film;

[0038] S4. Package the piezoelectric film and the sustained-release film with kapton tape to obtain a double-layer sustained-release antibacterial piezoelectric composite film.

[0039] Example 2

[0040] A preparation method of a double-layer sustained-release antibacterial piezoelectric composite film, comprising the following steps:

[0041] S1. Dissolve 500 mg of L-polylactic acid (purity 95%, molecular weight 22000) in 2 ml of dichloromethane (purity 95%), stir evenly, then add 3 ml of N,N-dimethylformamide (purity 95%), and finally add 50 mg of nano-zinc oxide and 75 mg of riboflavin (purity 95%), stir and dissolve for 10 h to obtain a spinning solution. Perform electrospinning on the spinning solution and dry it at 37 °C for 18 h to obtain a piezoelectric film;

[0042] S2. Add 750 mg of polyethersulfone (purity 95%) and 290 mg of polyvinylpyrrolidone to 5 ml of N,N-dimethylformamide, stir to dissolve for 12 h to obtain a spinning solution. Perform electrospinning on the spinning solution, and after drying at 37 °C for 18 h, obtain a polymer layer;

[0043] S3. Add 100 mg of poly(lactic-co-glycolic acid) and 10 mg of levofloxacin to 5 ml of N,N-dimethylformamide, stir to dissolve for 12 h to obtain a precursor solution, and then spray the precursor solution onto the surface of the polymer layer by electrospraying to obtain a sustained-release membrane;

[0044] S4. Package the piezoelectric membrane and the sustained-release membrane with kapton tape to obtain a double-layer sustained-release antibacterial piezoelectric composite membrane.

[0045] Example 3

[0046] A method for preparing a double-layer sustained-release antibacterial piezoelectric composite membrane, comprising the following steps:

[0047] S1. Dissolve 500 mg of poly-L-lactic acid (purity 95%, molecular weight 22000) in 2 ml of dichloromethane (purity 95%), stir evenly, then add 3 ml of N,N-dimethylformamide (purity 95%), and finally add 75 mg of nano-zinc oxide and 75 mg of riboflavin (purity 95%), stir to dissolve for 10 h to obtain a spinning solution. Perform electrospinning on the spinning solution, and after drying at 37 °C for 18 h, obtain a piezoelectric membrane;

[0048] S2. Add 750 mg of polyethersulfone (purity 95%) and 290 mg of polyvinylpyrrolidone to 5 ml of N,N-dimethylformamide, stir to dissolve for 12 h to obtain a spinning solution. Perform electrospinning on the spinning solution, and after drying at 37 °C for 18 h, obtain a polymer layer;

[0049] S3. Add 100 mg of poly(lactic-co-glycolic acid) and 10 mg of levofloxacin to 5 ml of N,N-dimethylformamide, stir to dissolve for 12 h to obtain a precursor solution, and then spray the precursor solution onto the surface of the polymer layer by electrospraying to obtain a sustained-release membrane;

[0050] S4. Package the piezoelectric membrane and the sustained-release membrane with kapton tape to obtain a double-layer sustained-release antibacterial piezoelectric composite membrane.

[0051] Comparative Example 1

[0052] A preparation method of a piezoelectric film, comprising the following steps: dissolving 500 mg of L-polylactic acid (purity 95%, molecular weight 22000) in 2 ml of dichloromethane (purity 95%), stirring evenly, then adding 3 ml of N,N-dimethylformamide (purity 95%), continuously stirring and dissolving for 10 h to obtain a spinning solution, performing electrospinning on the spinning solution, and drying at a temperature of 37 °C for 18 h to obtain a piezoelectric film.

[0053] Comparative Example 2

[0054] A preparation method of a polymer layer, comprising the following steps: adding 750 mg of polyethersulfone (purity 95%) and 290 mg of polyvinylpyrrolidone to 5 ml of N,N-dimethylformamide, stirring and dissolving for 12 h to obtain a spinning solution, performing electrospinning on the spinning solution, and drying at a temperature of 37 °C for 18 h to obtain a polymer layer.

[0055] Comparative Example 3

[0056] A preparation method of a piezoelectric film, comprising the following steps: dissolving 500 mg of L-polylactic acid (purity 95%, molecular weight 22000) in 2 ml of dichloromethane (purity 95%), stirring evenly, then adding 3 ml of N,N-dimethylformamide (purity 95%), and finally adding 50 mg of nano-zinc oxide and 75 mg of riboflavin (purity 95%), stirring and dissolving for 10 h to obtain a spinning solution, performing electrospinning on the spinning solution, and drying at a temperature of 37 °C for 18 h to obtain a piezoelectric film.

[0057] Performance testing

[0058] 1) Swelling performance testing

[0059] Dry the double-layer sustained-release antibacterial piezoelectric composite film prepared in Example 2, then cut it into a rectangle of 2 cm × 2 cm and weigh its mass when dry, denoted as Wd; then immerse the sample in PBS buffer (pH 7.4), and take it out after 0.2 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, blot the PBS buffer adhering to the film surface with paper, and weigh its mass, denoted as Ws. Measure the mass 3 times each time and take the average value. Calculate the swelling rate according to the following formula:

[0060] Swelling rate = (Ws - Wd) / Wd × 100%

[0061] The results are as Figure 1 shown.

[0062] From Figure 1It can be seen that the double-layer sustained-release antibacterial piezoelectric composite film prepared by the present invention has a good swelling rate. After soaking for 1 h, the swelling rate reaches more than 400%. The results show that when the double-layer sustained-release antibacterial piezoelectric composite film is used to prepare medical wound repair materials, due to its good swelling rate, it can better absorb the tissue fluid exuded from the wound.

[0063] 2) Piezoelectric performance test

[0064] The piezoelectric films prepared in Examples 1 to 3 and Comparative Example 1 were tested for output voltage using the built piezoelectric test platform under the action of a reciprocating motor with a fixed frequency and force.

[0065] First, the piezoelectric films prepared in Examples 1 to 3 and Comparative Example 1 were respectively cut into films with a size of 2 cm × 2 cm, and then arranged in the order of conductive aluminum foil, the above-mentioned cut film, and conductive aluminum foil to form a "sandwich" structure, which was encapsulated with kapton tape; signal acquisition was completed by an electrometer, and the signal was transmitted to a laptop for data collection. The results are as Figures 2 - 5 shown.

[0066] From Figure 2 it can be seen that the peak voltage of the piezoelectric film prepared in Comparative Example 1 is 3.21 V; from Figure 3 it can be seen that the peak voltage of the piezoelectric film prepared in Example 1 is 5.95 V; from Figure 4 it can be seen that the peak voltage of the piezoelectric film prepared in Example 2 is 10.56 V; from Figure 5 it can be seen that the peak voltage of the piezoelectric film prepared in Example 3 is 8.09 V.

[0067] The above results show that in the present invention, through the synergistic effect among poly(L-lactic acid), nano-zinc oxide, and riboflavin in the piezoelectric film, the piezoelectric performance of the piezoelectric film can be significantly improved.

[0068] 3) Antibacterial performance test

[0069] The immersion counting method was used to study the antibacterial activity of the materials against Staphylococcus aureus and Escherichia coli by calculating the number of colonies after diluting and coating the colonies.

[0070] Test bacteria: Staphylococcus aureus (Staphylococcus aureus ATCC6538), Escherichia coli (Escherichia coli ATCC25922).

[0071] The film samples prepared in Example 2 and Comparative Example 2 were respectively cut into an area of about 6 cm 2, small pieces of equal weight. Then mix with 1 mL of PBS bacterial suspension (the concentration of Escherichia coli is 1×10 7 CFU / mL or the concentration of Staphylococcus aureus is 1×10 8 CFU / mL) (using pure Staphylococcus aureus and Escherichia coli as control groups), and place them in a shaker at 37°C and mix for 1, 3, 6 h. After that, dilute the mixture 500 times and evenly spread it on LB agar plates. After incubating in a 37°C incubator for 24 h, inoculate 150 μL of Staphylococcus aureus suspension (OD value is 0.25 - 0.35) and Escherichia coli suspension (OD value is 0.25 - 0.35) onto the corresponding solid agar medium plates mentioned above, respectively cover the membrane samples in Example 2 and Comparative Example 2, and finally incubate at 37°C for 24 h. Observe the bacterial inhibition zone visually to detect the antibacterial activity of the samples, and the results are as Figure 6 and 7 shown.

[0072] As can be seen from Figure 6 , no antibacterial drug was added in Comparative Example 2, and it was found that the membrane in Comparative Example 2 had almost no antibacterial performance. The double-layer sustained-release antibacterial piezoelectric composite membrane prepared in Example 2 had a good antibacterial effect. Further, when the composite membrane was mixed with Escherichia coli bacterial liquid for 6 h, the antibacterial effect became significantly better. The results showed that the antibacterial drug in the composite membrane could be slowly released from the sustained-release membrane, improving the sustained-release antibacterial performance of the composite membrane.

[0073] As can be seen from Figure 7 , no antibacterial drug was added in Comparative Example 2, and it was found that the membrane in Comparative Example 2 had almost no antibacterial performance. The double-layer sustained-release antibacterial piezoelectric composite membrane prepared in Example 2 had a good antibacterial effect. Further, when the composite membrane was mixed with Staphylococcus aureus bacterial liquid for 6 h, the antibacterial effect became significantly better. The results showed that the antibacterial drug in the composite membrane could be slowly released from the sustained-release membrane, improving the sustained-release antibacterial performance of the composite membrane.

[0074] 4) In vitro cytotoxicity test

[0075] First, sterilize the double-layer sustained-release antibacterial piezoelectric composite membrane prepared in Example 2 and the piezoelectric membranes prepared in Comparative Examples 1 and 3, and then use them with a diameter of 6 mm 2Immerse them in complete medium (10% FBS (fetal bovine serum) + 1% PS (penicillin-streptomycin) + 89% DMEM) at a concentration of / mL for 24 h, then inoculate fibroblasts (NIH3T3 cells) into a 96-well plate at an inoculation density of 5000 cells / well. After culturing the plate in an incubator at 37 °C for 24 h, aspirate the medium, transfer the medium that has soaked the membrane to the 96-well plate, and continue culturing in the incubator. After 24 h, discard the medium, wash twice with PBS buffer, and then add a mixture of MTT (thiazolyl blue) and complete medium to each well in the dark. The mixing ratio of MTT to the medium is 1:9. After incubating at 37 °C for 4 h, carefully aspirate the supernatant, add 200 μL of dimethyl sulfoxide (DMSO) to each well to dissolve the blue-violet crystals at the bottom of the plate, and measure the absorbance at 490 nm using an enzyme-linked immunosorbent assay reader. Among them, the complete medium is the negative control group, and the mixture containing 10% phenol and the complete medium is the positive control group. The results are as Figure 8 shown.

[0076] As can be seen from Figure 8 this, the cell survival rates of the double-layer sustained-release antibacterial piezoelectric composite membrane prepared in Example 2, the piezoelectric membranes prepared in Comparative Examples 1 and 3 are 108.23%, 120.46% and 121.44% respectively. The results further show that the double-layer sustained-release antibacterial piezoelectric composite membrane prepared by the present invention has extremely low toxicity.

[0077] In summary, the composite membrane prepared in the present invention has good sustained-release characteristics, antibacterial properties, piezoelectric properties and biocompatibility, and can promote angiogenesis, wound healing and reduce inflammatory reactions. In addition, the raw materials in the present invention have good biocompatibility, wide sources, low prices, are easy to obtain, and the preparation process is simple. Therefore, it has good application prospects in the preparation of medical wound repair materials.

[0078] It should be noted that the above embodiments all belong to the same inventive concept. The descriptions of the embodiments have their own emphases. For the parts not described in detail in individual embodiments, reference can be made to the descriptions in other embodiments.

[0079] The above embodiments only represent the implementation manners of the present invention. The descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A double-layer slow-release antibacterial piezoelectric composite membrane, characterized in that It includes a piezoelectric film and a sustained-release film, and the piezoelectric film and the sustained-release film are encapsulated to obtain the double-layer sustained-release antibacterial piezoelectric composite film; Among them, the piezoelectric film includes poly(L-lactic acid), nano-zinc oxide and riboflavin; The sustained-release film includes a polymer layer and an antibacterial drug layer, and the antibacterial drug layer is coated on the surface of the polymer layer; In terms of mass percentage, the content of poly(L-lactic acid) is 8-15%, and the content of the polymer layer is 10-20%; and in the piezoelectric film, the mass ratio of poly(L-lactic acid), nano-zinc oxide and riboflavin is 1:(0.02-1):(0.1-0.5); The polymer layer includes polyethersulfone and polyvinylpyrrolidone; The antibacterial drug layer includes poly(lactic-co-glycolic acid) and levofloxacin.

2. The double-layer sustained-release antibacterial piezoelectric composite film according to claim 1, wherein The mass ratio of the polyethersulfone to the polyvinylpyrrolidone is 1:(0.2-0.5).

3. The double-layer sustained-release antibacterial piezoelectric composite film according to claim 1, wherein The mass ratio of the polylactic acid-glycolic acid to the levofloxacin is 1:(0.05~0.15); and the content of the levofloxacin on the surface of the polymer layer is 0.005~0.01 mg / cm 2 .

4. The double-layer sustained-release antibacterial piezoelectric composite film according to claim 1, characterized in that The purity of the poly(L-lactic acid) is 90-99%, and the molecular weight is 20000-24000; the purity of the riboflavin is 90-99%; the purity of the polyethersulfone is 90-99%.

5. The preparation method of the double-layer sustained-release antibacterial piezoelectric composite film according to any one of claims 1-4, characterized in that, It includes the following steps: Add poly(L-lactic acid), nano-zinc oxide and riboflavin into an organic solution and stir to dissolve to obtain a spinning solution. Perform electrospinning on the spinning solution, and after drying, obtain the piezoelectric film; Add polyethersulfone and polyvinylpyrrolidone into an organic solution and stir to dissolve to obtain a spinning solution. Perform electrospinning on the spinning solution, and after drying, obtain the polymer layer; Add poly(lactic-co-glycolic acid) and levofloxacin into an organic solution and stir to dissolve to obtain a precursor solution, and then coat the precursor solution on the surface of the polymer layer to obtain the sustained-release film; Encapsulate the piezoelectric film and the sustained-release film to obtain the double-layer sustained-release antibacterial piezoelectric composite film.

6. The preparation method of the double-layer sustained-release antibacterial piezoelectric composite film according to claim 5, characterized in that, In the preparation process of the piezoelectric film, the organic solution includes dichloromethane and N,N-dimethylformamide. The stirring and dissolving includes: the stirring and dissolving time is 6-12h, and the drying includes: the drying temperature is 30-45°C, and the time is 12-24h.

7. The preparation method of the double-layer sustained-release antibacterial piezoelectric composite film according to claim 5, characterized in that, In the preparation process of the polymer layer, the organic solution includes N,N-dimethylformamide. The stirring and dissolving includes: the stirring and dissolving time is 6-12h, and the drying includes: the drying temperature is 30-45°C, and the time is 12-24h.

8. The preparation method of the double-layer sustained-release antibacterial piezoelectric composite film according to claim 5, characterized in that, In the preparation process of the sustained-release film, the organic solution includes N,N-dimethylformamide. The stirring and dissolving includes: the stirring and dissolving time is 6-12h, and the coating includes: spraying by electrospray; the drying includes: the drying temperature is 30-45°C, and the time is 12-24h.

9. Application of the double-layer sustained-release antibacterial piezoelectric composite film according to any one of claims 1-4 in the preparation of medical wound repair materials.

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