Preparation And Properties Of Highly Stretchable And Adhesive Nanofibrous Hydrogel Dressing

In recent years,the commercially available dressings,such as film dressing,hydrocolloid dressings,and hydrogel dressings,have been developing rapidly.However,they were still limited to poor water retention,moisture permeability,poor skin adhesion,and inadequate mechanical properties.Therefore,it is emergency to develop ideal dressings to improve the comfortability and efficiency of promoting wound healing,which will have great research significance and important market value.Electrospinning is a general technology to prepare fibers with high porosity,small pore size,large specific surface area,and controllable morphology.By controlling the electrospinning parameters to regulate the pore size and porosity of nanofiber membrane,the nanofiber membrane with moisture and air permeability was obtained.It inherited the advantages of nanofibers and hydrogels for nanofiber-hydrogel,which have similar structures of natural extracellular matrix（ECM）to promote cell adhesion,proliferation,and differentiation.Additionally,the good moisture retention of hydrogel will be beneficial to the healing of wounds.Considering that it was difficult to maintain water and moisture permeability,ductility,and tissue adhesion for available dressings,this study reported a novel nanofibrous hydrogel with water holding capacity,moisture permeability,high extension,and tissue adhesion by electrospinning and in-situ reaction,based on natural polymer gelatin（GT）as raw material to introduce dopamine（DA）into GT.The morphology and mechanical properties of GT-DA nanofibrous hydrogel were optimized by adjusting the concentration of DA,crosslinking solvent ratio,and reaction time.Further,the adhesion of hydrogel can be improved by introducing Fe³⁺on the side of nanofibrous hydrogel.The experimental results showed that when the crosslinking solvent ratio and time up to9:1 and 8 h,the tensile strength of GT-DA nanofibrous hydrogel is the highest.Specifically,the breaking tensile strength was 1.96 MPa,which was 0.63 times higher than that of GT nanofibrous hydrogel.The shear bond strength between Gel-DA/Fe nanofibrous hydrogel and skin tissue can reach 2.46 KPa,which was 1.29 times than the commercial dressing Mepiform^?.To further enhance the mechanical properties of nanofibrous hydrogels,we have introduced carboxyl four-arm polyethylene glycol（4-arm-PEG-COOH）to produce interpenetrating network nanofibrous hydrogels with high extension properties.The water absorption,moisture permeability,and mechanical properties of GT-DA-PEG-COOH nanofibrous hydrogels were optimized by adjusting the composition of 4-arm-PEG-COOH.Impressively,the results showed that the nanofibrous hydrogels contain 4%4-arm-PEG-COOH had the best comprehensive properties,the breaking tensile strength was 3.78 MPa,and the young’s modulus was 1.86 MPa,which was 4.73times and 4.04 times of the primary GT nanofibrous hydrogel,respectively.The water absorption,moisture permeability,and moisture permeability were better than that of GT-DA nanofibrous hydrogel.The adhesion strength of Gel-DA-PEG-COOH/Fe nanofibrous hydrogel reached 2.91KPa,which was 1.52 times of the commercial dressing Mepiform^?,which solves the problem of poor fit between the existing dressing and the skin wound.In order to investigate the biocompatibility and wound healing ability of the nanofibrous hydrogel,the nanofiber hydrogel was cultured with fibroblasts cells（L929）in vitro,and implanted on the skin defect wound model in vivo.The results showed that L929 cells could adhere,survive,and proliferate on the surface of the nanofibrous hydrogel,which demonstrated its good biocompatibility.In addition,compared with gauze and commercially available dressing,Gel-DA-PEG-COOH/Fe could promote wound healing within 11 days after operation by promoting collagen deposition and accelerating wound closure speed.