Research Of A Self-assembled Peptide-based Nanofiber And PNIPAM Formed Thermo-sensitive Hydrogel For Wound Repair

As a wound dressing,hydrogels have appropriate viscosity,mechanical properties and good biocompatibility,so as a flexible functional material,hydrogels are widely used in wound healing.Thermosensitive hydrogel is a kind of intelligent hydrogel which has special sol-gel transition in different temperature.In low temperature,the low viscosity of solution phase can flow to fill the cavity,defects or surgical wound.Meanwhile,in body temperature,hydrogel which reduce the secondary injury to the wound can adapt to the border of irregular shape and be peeled off easily from the wound during dressing change.In addition,therapeutic agents such as drugs or cells can be quickly added to the system through simple solution mixing,and can also be used as a continuous carrier in drug release for local drug therapy or a cell growth matrix for tissue repair.Good wound dressings should meet the special needs of different healing stages,and the search for suitable hydrogel materials has become a hot spot of biomaterial research.This study selected the optimal formula of compound hydrogel PNI/RA-Amps,antibacterial characteristic of RADA16-Amps was determined by the coated plate method and the growth dynamics.Thermosensitive characteristic and mechanics performance of the composite hydrogel were determined by tube inversion method,ultraviolet spectrophotometer and rheological properties.Then,the proper composite hydrogel was screened by gelling time.The microscopic morphology of hydrogel was observed by SEM.The results showed that the RADA16-Amps conjugated with Amps retained the antimicrobial activity of Amps,and the inhibition rate of RADA16-Amps against E.coli and S.aureus reached 100% when the concentration of RADA16-Amps was 148.00μM.The optimum ratio of PNI/RA-Amps was 30mg/m L and 0.90μM,and the characteristics of temperature response were mainly related to PNIPAM.The system performed a porous network structure,which was conducive to the exchange of gas and liquid,hemostasis,wound healing,drug release,etc.By constructing PNI/RA-Amps and drug-loaded PNI/RA-Amps/E,the sustained-release properties of MGF E peptides were tested,and the effects of PNI/RA-Amps/E on cell function were studied.The results showed that the relative cell proliferation rate of composite hydrogel in different concentrations was more than80% and hemolysis rate was less than 5%,which meant the national safety standard and had good biocompatibility.The composite hydrogels could be loaded with MGF E peptide,which could be continuously released in vitro for 24 h.The optimal loading concentration of MGF E peptides was 50.00ng/m L,and the proliferation of HFF cells was significantly promoted at 48h(P<0.01).At the same time,the addition of PNI/RA-Amps improved the cell adhesion of the composite hydrogel(P<0.01).Hepatic hemostasis model was established in mice to test the effect of temperature-sensitive hydrogel on hemostasis.The effects of temperature-sensitive hydrogels on tissue adhesion property in vitro and in vivo were investigated by stretching and inverting pig skin and rat wounds.To study the effect of thermo-sensitive hydrogel on wound repair in rat skin wound model.The result showed that the thermo-sensitive hydrogel significantly accelerated hemostasis(P<0.01)and the hemostasis effect was significantly better than that of commercial liquid wound dressing(P<0.05).PNI/RA-Amps in situ hydrogel can be firmly adhered to the rat wound surface and the pig skin treated with stretch and inversion after forming hydrogel expressed good adhesion and be used to cover skin wound surface.During the skin wound repair process,observing the skin pathological changes,the drug loaded PNI/RA-Amps/E hydrogel reduced the aggregation of inflammatory cells at the wound site,accelerated the epithelialization,generated new blood vessels,promoted the generation of collagen fiber and promoted the wound healing.In this research,the self-assembled peptide RADA16 with hemostatic properties and the short antimicrobial peptide Amps were screened out and conjugated into a peptide chain.In the aqueous solution,the self-assembled peptide fiber with both hemostatic and bacteriostatic properties was prepared.By blending with the thermo-sensitive copolymer PNIPAM,the composite hydrogel had both thermo-sensitive properties and excellent mechanical properties.The vitro experiments and animal experiments were detected the skin wound healing in the body function.The study showed that PNI/RA-Amps thermosensitive hydrogel had good biocompatibility,loaded MGF E peptide and slowed release.PNI/RA-Amps/E hydrogel promoted the proliferation of HFF cells and the repair of skin damage which was an excellent biological material,providing theoretical basis for clinical application and the direction.