Double-sided asymmetric multifunctional composite patch and preparation method thereof

Abstract

The invention relates to the technical field of surgical medical biological materials, and particularly discloses a double-sided asymmetric multifunctional composite patch and a preparation method thereof, which adopt self-induced phase separation, solvent replacement and in-situ photo-crosslinking technologies to safely and efficiently improve the performance of the patch. Therefore, the anti-pollution and anti-sticking adhesive tape has multiple functions of deformation resistance, degradation resistance, infection resistance, pollution resistance, adhesion resistance, healing promotion and the like. The obtained double-sided asymmetric multifunctional composite patch is of a two-layer structure, the rough and porous surface of the substrate layer is improved, the substrate layer is similar to an extracellular matrix skeleton, and tissue repair and wound healing are promoted; the bPVA layer is formed by grafting PVA molecules with zwitterions, the surface aperture is small, a hydration layer is formed, and adhesion of intestinal canals and other viscera is effectively prevented. Experiments show that the patch is excellent in deformation resistance and degradation resistance in an in-vivo wet environment, good in integrity after operation for 14 days, and free of complications. The patch is suitable for clinical scenes accompanied by infection, particularly meets the complete-cycle functional requirements of infectious abdominal wall defect repair, and has remarkable clinical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of surgical medical biomaterials, and more specifically, to a double-sided asymmetric multifunctional composite patch and a preparation method thereof. Background Art

[0002] Infectious abdominal wall defects pose a great therapeutic challenge due to the complex contaminated microenvironment. Commercial biological patches with anti-adhesion properties and certain tissue reconstruction capabilities, such as small intestinal submucosa acellular matrix (SIS) and basement membrane (BM), are considered to be one of the most promising materials for repairing infectious abdominal wall defects. However, the above biological patches have limitations in controlling infections and are prone to rapid degradation in vivo, resulting in a significant reduction in their mechanical strength, thereby causing serious complications such as postoperative local abscesses, secondary peritoneal adhesions, and high recurrence rates.

[0003] Different from superficial tissue injuries such as skin wounds, the microenvironment of infectious abdominal wall defects is a complex system usually caused by multiple factors. It is crucial to endow biological patches with multiple biological activities, including antibacterial ability, anti-adhesion ability, and pro-healing activity. In addition, its degradation process should be well controlled to provide continuous mechanical support throughout the tissue reconstruction process. Generally speaking, the repair of infectious abdominal wall soft tissues requires the implanted material to have excellent antibacterial ability; at the same time, the complex peritoneal microenvironment requires the implanted material to maintain excellent biocompatibility and have anti-adhesion ability. Despite a great deal of effort in this field, few patches can achieve these conflicting properties simultaneously. Many studies usually focus on enhancing the antibacterial biological activity of biomaterials, but their antibacterial components may cause cytotoxicity and even trigger secondary organ adhesions. For example, the metabolic activities of bacteria and their subsequent death during the antibacterial process can trigger the release of inflammatory adhesion factors, promote fibrin deposition, and promote the formation of biofilms, ultimately leading to peritoneal adhesions and impaired healing. For the preparation of high-performance patches, traditional surface chemical modification strategies often lead to collagen denaturation, adversely affecting its chemical and physical structures, thereby weakening its anti-infection ability; simple component strategies usually result in weak interfacial interactions between various functional components, hindering the synergistic realization of multiple biological activities.

[0004] Therefore, on the premise of ensuring tissue reconstruction ability, it is crucial to prepare biocompatible patches with excellent anti-infection ability and anti-fouling and anti-adhesion properties for the development of new repair materials for infectious abdominal wall defects. Summary of the Invention

[0005] The present invention aims to overcome at least one of the above-mentioned deficiencies in the prior art, and provides a double-sided asymmetric multifunctional composite patch and a preparation method thereof, which are used to comprehensively consider functions of anti-deformation, anti-degradation, anti-infection, anti-fouling and anti-adhesion, and pro-healing during the whole cycle of local infectious abdominal wall defect repair.

[0006] The technical solution adopted by the present invention is to provide a method for preparing a double-sided asymmetric multifunctional composite patch, comprising the steps of:

[0007] S1, dissolving PVA in an organic solvent to form a PVA solution, thermally initiating the grafting of zwitterionic monomers in an oxygen-free environment at a constant temperature, and precipitating and washing after sufficient reaction to obtain a product bPVA;

[0008] S2, immersing the biological patch in a dopamine solution, and then moving the patch to a polyethyleneimine solution for post-modification to obtain an improved basal layer;

[0009] S3, dissolving the bPVA obtained in step S1 in an organic solvent to obtain a bPVA solution; spreading the improved base layer obtained in step S2 on the bPVA solution, drying, hydrating, and washing to obtain a double-layer hydrogel as the double-sided asymmetric multifunctional composite patch.

[0010] The above preparation method is based on the existing biological patch and common material PVA, and uses zwitterionic monomers to graft and modify it, and further modifies it, thereby improving the multiple functions of the patch and avoiding or reducing the occurrence of complications after infectious abdominal wall defect repair surgery.

[0011] Step S1 uses in-situ photocrosslinking technology to graft zwitterions on PVA to obtain bPVA with greatly optimized performance, making it suitable for clinical scenarios accompanied by infection. In terms of anti-fouling and anti-adhesion properties, zwitterionic monomers such as methacryloyl sulfobetaine (SBMA) have hydrophilic and electrically neutral properties, can form a surface lubricated hydration layer, and effectively resist the nonspecific adsorption of proteins, bacteria and other biological molecules. This property makes the surface of the material grafted with zwitterionic monomers have excellent anti-fouling and anti-adhesion properties, reducing the adhesion of the patch to the surrounding tissue when used in vivo. In terms of anti-infection performance, due to the electrically neutral properties of zwitterionic monomers, it is difficult for bacteria to attach and reproduce on the surface of the material, thereby reducing the risk of infection; in addition, the modification of dopamine and polyethyleneimine brings positive charges to the amino group, further enhancing the antibacterial effect of the material. In terms of promoting healing performance, zwitterionic monomers have good biocompatibility, can reduce the immune rejection reaction of the material in the body, and are conducive to tissue healing. In terms of anti-degradation performance, the chemical stability and mechanical properties of PVA materials are enhanced by grafting zwitterionic monomers, which can resist enzymatic hydrolysis or oxidation in the body, thereby extending the service life of the patch. In terms of anti-deformation performance, the grafting of zwitterionic monomers can improve the mechanical properties of the material, making it less likely to deform when subjected to mechanical stress in the body, and maintaining the integrity of the structure.

[0012] In step S2, the biological patch is modified to further enhance its antibacterial performance. Since polyethyleneimine (PEI) is a high molecular polymer containing a large number of amino groups and has a positive charge property, PEI can interact with the negatively charged bacterial cell membrane and destroy the bacterial cell membrane structure. Therefore, the patch modified with PEI can exhibit excellent antibacterial performance. In more than one embodiment of the present invention, it is found by testing that the antibacterial rates of the patches prepared by the above method against Escherichia coli and Staphylococcus aureus both reach more than 98%.

[0013] In step S3, self-induced phase separation and solvent replacement are used to combine the above two layers of materials into one body to form a double-sided asymmetric composite structure. The improved base layer is laid flat on the bPVA solution. Since both the improved base layer itself and the air contain moisture, the water and the organic solvent in the bPVA solution are exchanged, resulting in the inversion of the bPVA polymer molecules to form a hydrogel. The obtained hydrogel has a two-layer structure. The bPVA layer is composed of PVA molecules grafted with zwitterions, with a small surface pore size and a hydrated layer formed. When applied in abdominal wall repair, it should face the abdominal cavity side, and can maintain stable anti-pollution and corresponding anti-adhesion performance in a contaminated environment; the surface of the improved base layer is rough and porous, similar to the extracellular matrix skeleton, suitable for cell adhesion and crawling. When applied in abdominal wall repair, it should face the abdominal wall wound to promote tissue repair and wound healing, and show strong contact antibacterial ability with the help of the surface positive charge in the acute stage of repair. The in-situ combination of the two-layer structure can bring high and stable burst pressure resistance. By comprehensively controlling bacteria and their necrotic products, the obtained double-sided asymmetric multifunctional composite patch can achieve anti-infection, anti-adhesion and wound healing promotion performance in infectious abdominal wall defects.

[0014] Furthermore, in step S1, the concentration of the PVA solution is 5-20%, the degree of polymerization of PVA ranges from 100 to 4500, and the degree of alcoholysis ranges from 88% to 99%; the concentration of the zwitterionic monomer is 5-20%, the molar ratio of the thermal initiator to the zwitterionic monomer is 0.3-3%, the temperature is 60-80 °C, and the reaction time is 12-36 h. Setting the above range limits is beneficial to obtaining an asymmetric porous hydrogel with better mechanical properties, anti-swelling properties and anti-degradation properties, and achieving the technical effect of anti-deformation in the in-vivo wet environment. In more than one embodiment of the present invention, when the patch prepared by the above method is applied in abdominal wall repair, the integrity of the patch is good at 14 days after surgery, and no complications caused by premature degradation occur.

[0015] Preferably, the degree of polymerization of PVA is 1700 and the degree of alcoholysis is 99%.

[0016] Preferably, the PVA type is PVA-1799 and the concentration is 10%. Within a certain range, as the degree of polymerization and alcoholysis of PVA increase, the viscosity of the PVA / DMSO solution increases, while the solubility of PVA decreases, and finally the mechanical strength and uniformity of the obtained PVA hydrogel will be affected.

[0017] Furthermore, the organic solvent is dimethyl sulfoxide DMSO. The specific operation of dissolving PVA in step S1 is to add PVA and DMSO into a round-bottom flask, and then place it in an oil bath at 70°C and stir for 2 h until completely dissolved.

[0018] Furthermore, the anaerobic environment in step S1 is one of N2, Ar, He or a vacuum environment.

[0019] Preferably, the anaerobic environment is N2.

[0020] Furthermore, the zwitterionic monomer in step S1 is methacryloyl sulfobetaine, acryloyl sulfobetaine, N-vinyl-N-methyl-N-(3-sulfopropyl)-N-(3-methacryloyloxy)propyl ammonium chloride or N-(3-methacryloyloxy)propyl-N,N,N-trimethyl ammonium chloride; the thermal initiator is ammonium cerium nitrate.

[0021] Preferably, the zwitterionic monomer is methacryloyl sulfobetaine and the thermal initiator is ammonium cerium nitrate.

[0022] Furthermore, the concentration of the zwitterionic monomer is 5-20%, the molar ratio of the thermal initiator to the zwitterionic monomer is 0.3-3%, the temperature is 60-80°C, and the reaction time is 12-36 hours.

[0023] Preferably, the concentration of the zwitterionic monomer is 10%, and the molar ratio of the thermal initiator to the zwitterionic monomer is 2.5%.

[0024] Furthermore, the biological patch in step S2 is porcine small intestinal submucosa acellular matrix, bladder basement membrane and / or acellular dermal matrix.

[0025] Furthermore, the concentration of the dopamine solution in step S2 is 1.5-3 g / L, the immersion time in the dopamine solution is 12-36 h, the concentration of the polyethyleneimine solution is 3-8 g / L, and the immersion time in the polyethyleneimine solution is 6-24 h.

[0026] Preferably, the immersion time in the dopamine solution is 24 hours, the concentration of the polyethyleneimine solution is 4 g L-1, and the immersion time in the polyethyleneimine solution is 6 hours.

[0027] Furthermore, the concentration of the bPVA solution in step S3 is 10-30%, SIS +The duration of paving is 12 - 36 h.

[0028] Furthermore, the drying is air drying, the air drying temperature is 20 - 50 °C, and the air drying time is 12 - 36 hours.

[0029] Furthermore, the preparation method further includes step S4: sterilizing the bPVA / SIS obtained in step S3, and dropping cytokines on one surface of SIS. The cytokines are nicotinamide phosphoribosyltransferase, acidic fibroblast growth factor, chondroitin sulfate, and / or epidermal growth factor. This is beneficial to further enhance the performance of the double-sided asymmetric multifunctional composite patch in promoting tissue repair and wound healing. + sterilization treatment, dropping cytokines on the surface of SIS + One side surface drops cytokines. The cytokines are nicotinamide phosphoribosyltransferase, acidic fibroblast growth factor, chondroitin sulfate, and / or epidermal growth factor. It is beneficial to further enhance the performance of the double-sided asymmetric multifunctional composite patch in promoting tissue repair and wound healing.

[0030] Another object of the present invention is to provide a double-sided asymmetric multifunctional composite patch obtained by the above preparation method.

[0031] Another object of the present invention is to provide the application of the above double-sided asymmetric multifunctional composite patch in the preparation of soft tissue defect patches.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The present invention provides a double-sided asymmetric multifunctional composite patch and its preparation method. By using self-induced phase separation, solvent replacement, and in-situ photocrosslinking technologies, the performance of the patch is safely and efficiently improved, enabling it to have multiple functions such as anti-deformation, anti-degradation, anti-infection, anti-fouling and anti-adhesion, and promoting healing. The obtained double-sided asymmetric multifunctional composite patch has a two-layer structure. The surface of the improved base layer is rough and porous, similar to the extracellular matrix skeleton, which promotes tissue repair and wound healing. The bPVA layer is composed of PVA molecules grafted with zwitterions, with small surface pores and a hydrated layer formed, effectively preventing visceral adhesions such as intestinal tubes. Experiments show that the patch has excellent anti-deformation and anti-degradation performance in the in-vivo wet environment, and its integrity is good 14 days after surgery, without complications. The patch is suitable for clinical scenarios with infections, especially meeting the full-cycle functional requirements for the repair of infectious abdominal wall defects, and has significant clinical application value. Description of the Drawings

[0034] Figure 1 is the preparation flow chart of the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP.

[0035] Figure 2 is the FTIC-ATR infrared spectrogram of the double-sided asymmetric multifunctional composite patch bPVA and SIS +

[0036] Figure 3 is the double-sided asymmetric multifunctional composite patch SIS​+ Photograph of the physical object showing the self-induced phase transition leading to the gelation of bPVA.

[0037] Figure 4 SEM images of each layer of the double-sided asymmetric multifunctional composite patch.

[0038] Figure 5 Tensile stress-strain diagram of the double-sided asymmetric multifunctional composite patch.

[0039] Figure 6 a shows the antibacterial plate test diagram of the double-sided asymmetric multifunctional composite patch against Escherichia coli and Staphylococcus aureus. Figure 6 b shows the antibacterial rates of the patch against Escherichia coli and Staphylococcus aureus.

[0040] Figure 7 Diagram of anti-fouling and anti-cell adhesion of the double-sided asymmetric multifunctional composite patch.

[0041] Figure 8 ELISA method for detecting the release rate of NP in the double-sided asymmetric multifunctional composite patch bPVA / SIS+-NP.

[0042] Figure 9 CCK 8 kit for testing the cytotoxicity of the double-sided asymmetric multifunctional composite patch bPVA / SIS+-NP.

[0043] Figure 10 Diagram of the experimental situation at the abdominal wall repair site during and 14 days after animal abdominal wall repair surgery. Detailed implementation mode

[0044] It should be noted that the following detailed description is illustrative and aims to provide further explanation for this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0045] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0046] The present invention will be further described below in conjunction with specific examples. The following examples are only for explaining the present invention and do not constitute a limitation to the present invention. In the following examples, if the specific experimental conditions are not indicated, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; for the reagents, consumables, etc. used in the examples, unless otherwise specified, they can all be obtained from commercial channels.

[0047] Example 1

[0048] As Figure 1 shown, prepare the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP, the steps are as follows:

[0049] S1. Dissolve PVA powder in DMSO to form a PVA solution, and thermally initiate the grafting of zwitterionic monomers in an anaerobic environment and at a constant temperature. After sufficient reaction, precipitate and wash to obtain the product bPVA.

[0050] S2. Immerse the acellular matrix of porcine small intestinal submucosa (SIS) biological patch in dopamine solution, and then transfer the patch to polyethyleneimine solution for post-modification to obtain SIS + .

[0051] S3. Dissolve the bPVA obtained in step S1 in an organic solvent; lay the SIS obtained in step S2 + flat on the bPVA / DMSO solution, then air-dry, hydrate, and wash away the residual solvent to obtain bPVA / SIS + .

[0052] S4. After sufficient disinfection and sterilization, add the cytokine nicotinamide phosphoribosyltransferase (NAMPT, abbreviated as NP below) dropwise to the SIS + surface of bPVA / SIS to obtain the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP. + -NP.

[0053] Among them, the specific operation of step S1 is: add PVA and DMSO to a round-bottom flask, and then place it in an oil bath at 70 °C and stir for 2 h until completely dissolved.

[0054] Among them, the PVA model is PVA-1799, and the concentration is 10%.

[0055] Among them, the anaerobic environment in step S1 is N2, the concentration of zwitterionic monomer is 10%, and the molar ratio of thermal initiator to zwitterionic monomer is 2.5%. The temperature is 60-80 °C, and the reaction time is 12-36 hours. The zwitterionic monomer is methacryloyl sulfobetaine, and the thermal initiator is ammonium cerium nitrate.

[0056] Among them, the concentration of the dopamine solution in step S2 is 2 g / L, the immersion time in the dopamine solution is 24 hours, the concentration of the polyethyleneimine solution is 4 g / L, and the immersion time in the polyethyleneimine solution is 6 hours.

[0057] Among them, the organic solvent in step S3 is DMSO, the bPVA concentration is 20%, and SIS + is laid flat on bPVA / DMSO for 12 hours, the air-drying temperature is 37 °C, the air-drying time is 24 hours, and the hydration time is 24 h.

[0058] Example 2

[0059] Using the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP obtained in Example 1 as a test sample for structural characterization and performance testing, the process and results are as follows.

[0060] 1. Fourier transform attenuated total reflection infrared spectroscopy characterization

[0061] Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) was used to study the structural changes from PVA to bPVA. As Figure 2 shown, new peaks appeared in the ATR-FTIR spectrum of bPVA at 1035 and 1176 cm-1, which can be attributed to the stretching vibration bands of sulfonic acid groups (S-O and S=O), and there is also a new peak at 1724 cm-1, referring to the stretching vibration of the carbonyl group (C=O). The absence of the carbon-carbon double bond (C=C) at approximately 1635 cm-1, which is usually associated with the sulfobetaine methacrylate (SBMA) monomer, indirectly confirmed the successful polymerization and grafting of PSBMA onto the PVA backbone.

[0062] To improve the antibacterial and anti-degradation properties of SIS, it was first functionalized by doping with polydopamine (SIS@PDA), manifested as a color change from white to black, and at the same time a characteristic peak of the substituted aromatic ring appeared at 798 cm-1. Further modification was carried out by soaking in polyethyleneimine for 6 hours, enhancing the methylene peak at 2825 cm-1, which was confirmed by the ATR-FTIR spectrum. These new peaks indicate that polyethyleneimine was successfully grafted onto the polydopamine layer, thus obtaining cationic SIS@PDA-PEI (SIS + )

[0063] 2. Gelation principle and morphological characteristics

[0064] By simply wetting the SIS +Coated on bPVA in dimethyl sulfoxide (DMSO) solution, the bPVA chains gelate during the self-induced phase separation process. After air drying and hydration, bPVA / SIS + composite patches can be obtained. As Figure 3 shown, under the condition of separating the moisture in the air with transparent adhesive tape, the aqueous solution in SIS + diffuses downward into the bPVA / DMSO solution and induces phase separation of the bPVA chains, forming a dense hydrogen bond network at the interface with SIS + , thus initially forming the composite patches. As Figure 4 shown by SEM, the bPVA / SIS + composite patches have a dense and porous bPVA layer and a loose and macroporous SIS + layer, and the combination between the two interfaces is tight.

[0065] 3. Mechanical tests

[0066] An ideal patch should have good mechanical properties and anti-swelling properties to withstand the maximum abdominal pressure of 0.02 MPa during abdominal wall defect repair. A universal mechanical testing machine (WD-5A, Guangzhou Experimental Instrument Factory, China) was used to conduct tensile tests to characterize the mechanical properties of the composite patches. Its tensile strength is 0.97 MPa. Under a tensile strain of 30%, the cyclic loading tensile stress is 0.23 - 0.29 MPa, which can meet the requirements for mechanical support in abdominal wall repair ( Figure 5 ). The bPVA / SIS + -NP patches with excellent mechanical properties, anti-swelling properties and anti-degradation properties can meet the mechanical requirements for in-vivo abdominal cavity implantation in vitro.

[0067] 4. Antibacterial properties

[0068] Antibacterial property is the primary requirement for patch materials applied to infectious abdominal wall defects. To evaluate the antibacterial property of bPVA / SIS + -NP patches, contact antibacterial experiments were carried out by adding Staphylococcus aureus and Escherichia coli culture media to the SIS + -NP layer of bPVA / SIS + patches. The results are as Figure 6 shown. Almost no Staphylococcus aureus and Escherichia coli can be found in the bPVA / SIS + NP group, while a large number of Staphylococcus aureus and Escherichia coli are found in the clinically commonly used basement membrane (BM) group. The antibacterial rates of bPVA / SIS + -NP patches against Escherichia coli and Staphylococcus aureus are 98.5% and 99.4% respectively.

[0069] 5. Anti-fouling tests

[0070] The effects of bacterial contamination and deposited proteins on repair materials may lead to severe visceral adhesions and delay the healing of defects. Therefore, the stable anti-pollution performance of repair materials is crucial for their application in infected microenvironments. However, the existing commercial patches with anti-pollution coatings (such as polycarbonate) have poor interfacial binding force, and the coatings are prone to peeling off. To evaluate the stable anti-pollution performance of our bPVA / SIS + -NP patch, Escherichia coli expressing green fluorescent protein (GFP) (107 CFU mL -1 ) and fibrin labeled with 6-FAM SE (1 mg mL -1 ) were selected as representative pollution sources and incubated with different samples for 12 hours, and then the surface was observed with a fluorescence microscope.

[0071] The results are as Figure 7 shown. Compared with BM and PVA hydrogel patches, the intact bPVA layer of the bPVA / SIS + -NP patch showed significantly less Escherichia coli and fibrin contamination. More importantly, after scraping off part of the bPVA layer of the bPVA / SIS + -NP patch with a scalpel, even if the bPVA layer was defective, the patch could still maintain excellent anti-pollution performance against Escherichia coli and fibrin.

[0072] To further clarify the anti-adhesion performance of our double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP in an infected environment, after immersing the samples in a biocontaminated solution containing heat-inactivated Escherichia coli and fibrin for 12 hours, L929 cells (3×10 4 mL -1 ) were inoculated onto the surfaces of different samples for 12 hours. Whether contaminated by heat-inactivated Escherichia coli and fibrin or not, commercial BM and SIS + -NP would cause a large number of L929 cells to adhere. In contrast, few L929 cells were found on the intact layer and defective layer of our bPVA / SIS + -NP patch with or without heat-inactivated Escherichia coli and fibrin contamination.

[0073] 6. Drug release and biocompatibility experiments

[0074] The release rate of NP in the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP was detected by the Elisa method. The results are as Figure 8 shown. NP could be slowly released within 10 days, demonstrating that bPVA / SIS +- The NP patch has the effect of delaying drug release. The cytotoxicity of the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP was tested by a CCK 8 kit, and the results are as Figure 9 shown: Compared with the commonly used BM patch group in clinical practice, there was no significant difference in the proliferation of L929 fibroblasts in the PVA1 group of the double-sided asymmetric multifunctional composite patch on the first day, and the proliferation was faster on the second and third days. This was attributed to the pro-proliferative function of NP on L929 fibroblasts after release, demonstrating that the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP has good biocompatibility and wound-healing promotion function.

[0075] 7. Animal experiment on the repair of infectious abdominal wall defects

[0076] Sprague-Dawley rats were used as experimental animals to evaluate the role of the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP in preventing adhesions and promoting healing of infectious abdominal wall defects. The rats were anesthetized by intraperitoneal injection of 3% sodium pentobarbital (1.5 mL / kg -1 ). Using a sterile surgical procedure, a 10-mm full-thickness defect was created on the abdominal wall with a round punch. To simulate contamination, the defect site was inoculated with 100 μL of Escherichia coli (10 7 CFU / mL -1 ) suspension for 1 minute, and then the excess was wiped off with a sterile gauze. Subsequently, different types of patches (the commonly used BM in clinical practice and the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP) were applied to the defect site to evaluate their tissue regeneration ability and adhesion prevention ability. The patches were fixed with 4-0 silk threads, and the abdominal wall incision was also sutured with 4-0 silk threads. After 14 days, the abdomen was opened to observe the presence of adhesions, the severity of adhesions, wound healing, wound infection, and the status of the patches, etc. Among them, Figure 10 shows the experimental situation of the abdominal wall repair site during and 14 days after local infectious abdominal wall defect repair surgery.

[0077] The results showed that the anatomical experiment showed that there were no adhesions of organs such as the small intestine and liver at the patch repair sites, the defects healed well, there was no obvious infection, no encapsulated effusion, empyema, and scar, the patches showed no obvious deformation, and the soft tissues at the defect sites fit well with the patches. It shows that the double-sided asymmetric multifunctional composite patch bPVA / SIS + -NP can fully meet the needs of local infectious abdominal wall defect repair, and has good antibacterial, anti-adhesion, and wound-healing promotion effects, can efficiently repair soft tissue defects, significantly improve the success rate of the repair surgery, and reduce the complication and recurrence rates.

[0078] The above test results show that the preparation method provided in Example 1 can construct a porous structure multifunctional hydrogel with antibacterial, antifouling, and promoting healing properties. The bPVA layer can maintain stable anti-pollution and corresponding anti-adhesion properties in a polluted environment; on the basis of retaining the original extracellular matrix skeleton, SIS + -NP layer exhibits strong contact antibacterial ability in the acute stage of repair and realizes sustained release of drugs in the healing stage of repair. The in-situ combination of the bPVA layer and SIS + -NP layer can bring high and stable burst pressure resistance. By comprehensively controlling bacteria and their necrotic products, the bPVA / SIS + -NP patch can achieve anti-infection, anti-adhesion, and promoting healing properties in rat infectious abdominal wall defects.

[0079] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, rather than limitations on the specific implementation manners of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A preparation method of a double-sided asymmetric multifunctional composite patch, characterized in that, Including the steps: S1. Dissolve PVA in an organic solvent to form a PVA solution, and under an anaerobic environment and at a constant temperature, thermally initiate grafting of zwitterionic monomers. After sufficient reaction, precipitate and wash to obtain the product bPVA; S2. Immerse the biological patch in a dopamine solution, and then transfer the patch to a polyethyleneimine solution for post-modification to obtain an improved base layer; S3. Dissolve the bPVA obtained in step S1 in an organic solvent to obtain a bPVA solution; lay the improved base layer obtained in step S2 flat on the bPVA solution, dry, hydrate, and wash to obtain a double-layer hydrogel as the double-sided asymmetric multifunctional composite patch.

2. The preparation method according to claim 1, wherein, In step S1, the concentration of the PVA solution is 5-20%, the degree of polymerization of PVA ranges from 100 to 4500, and the degree of alcoholysis ranges from 88% to 99%; the concentration of the zwitterionic monomer is 5-20%, the molar ratio of the thermal initiator to the zwitterionic monomer is 0.3-3%, the temperature is 60-80°C, and the reaction time is 12-36 h.

3. The preparation method according to claim 1, characterized in that, The zwitterionic monomer described in step S1 is methacryloyl sulfobetaine, acryloyl sulfobetaine, N-vinyl-N-methyl-N-(3-sulfopropyl)-N-(3-methacryloyloxy)propyl ammonium chloride, or N-(3-methacryloyloxy)propyl-N,N,N-trimethyl ammonium chloride; the thermal initiator is ammonium cerium nitrate.

4. The preparation method according to claim 1, characterized in that, The biological patch described in step S2 is porcine small intestinal submucosa acellular matrix, bladder basement membrane, and / or acellular dermal matrix.

5. The preparation method according to claim 1, characterized in that, In step S2, the concentration of the dopamine solution is 1.5-3 g / L, the immersion time in the dopamine solution is 12-36 h, the concentration of the polyethyleneimine solution is 3-8 g / L, and the immersion time in the polyethyleneimine solution is 6-24 h.

6. The preparation method according to claim 1, characterized in that, In step S3, the concentration of the bPVA solution is 10-30%, and the duration of laying the improved base layer flat is 12-36 h.

7. The preparation method according to claim 1, characterized in that, It further includes step S4. Sterilize the double-layer hydrogel obtained in step S3, and drop cytokines on one surface of the improved base layer.

8. The preparation method according to claim 7, characterized in that, The cytokines described in step S4 are nicotinamide phosphoribosyltransferase, acidic fibroblast growth factor, chondroitin sulfate, and / or epidermal growth factor.

9. A double-sided asymmetric multifunctional composite patch obtained by using the preparation method according to any one of claims 1 to 8.

10. Use of the double-sided asymmetric multifunctional composite patch according to claim 9 in the preparation of a soft tissue defect patch.

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