Preparation And Properties Of Gelatinbased Composite Nanofibrous Hydrogels For Wound Dressings

Wound healing is a complex and dynamic process,and the properties of dressing are particularly important for accelerating wound healing.Due to the high porosity and surface area ratio and mimicry of natural extracellular matrix,electrospun nanofibers are able to promote air permeability and skin wound repair.The hydrogels with good water absorption ability are able to absorb wound exudate and keep a moist environment in the wound site,benefiting wound healing.Nanofibrous hydrogels,which combined the structural advantages and functional properties of nanofibers and hydrogels,could act as an ideal candidate for wound dressings.Although gelatin fibrous hydrogels have good biocompatibility,their low mechanical property and tissue-adhesive property result in poor adhesion stability to skin wounds during motion.Therefore,there is an urgent need to develop gelatin-based nanofibrous hydrogel with good tensile property and tissue-adhesive property for suitable wound dressings during motion.First,with the aim to improve mechanical property of gelatin fibrous hydrogel,cystamine dihydrochloride（CYS）and dopamine（DA）was conjugated with gelatin（Gel）followed by and electrospinning to prepare nanofiber membranes.Then the nanofiber membranes were further crosslinked in an alkaline environment to obtain Gel-CYS-DA fibrous hydrogels.With the aid of cross-linking molecules and the step-by-step cross-linking strategy,the cross-linking density in the network structure was elevated,leading to increased cohesion,which could improve the mechanical property.The tensile test results showed that the Gel-2%CYS-DA fibrous hydrogel had the highest tensile strength at break,reaching 2.92 MPa,which was 2.5 times that of Gel.And it showed good fatigue resistance in 50 cyclic tensile experiments.The cell live/dead,cell proliferation,and cell morphology showed that the fibrous hydrogels had good biocompatibility,indicating that the GelCYS-DA fibrous hydrogel would be a good candidate for wound dressing.Then,with the aim to improve adhesion of gelatin fibrous hydrogel,the dithiothreitol（DTT）was used to reduce the disulfide bonds in the Gel-CYS to prepare thiolated gelatin（Gel-SH）,and then Gel-SH and DA were reacted and electrospun in an acidic environment,followed by further crosslinking in an alkaline environment to obtain Gel-SH-DA fibrous hydrogel.The tensile test results showed that the Gel-SH-DA fibrous hydrogel exhibited a tensile strength at break of 2.10 MPa and an elongation of 132%.The lap shear adhesion test results showed that the adhesion strength of Gel-SH-DA fibrous hydrogel was 4.33 k Pa,which was 2.8 times that of Gel.The free sulfhydryl groups in Gel-SH-DA could react with sulfhydryl groups on tissues to form disulfide bonds,and the catechol group and oxidized o-quinone group in dopamine could generate covalent bonds and hydrogen bonds with the functional groups on the tissue surface.Therefore,the increased cohesion and interfacial adhesion led to improved tissue-adhesion of fibrous hydrogels.In summary,we prepared gelatin-based fibrous hydrogels by electrospinning technology.By introducing cross-linking molecules or tissue-adhesion groups such as catechol and sulfhydryl groups into gelatin molecules and the step-by-step cross-linking strategy,we prepared fibrous hydrogels with good mechanical property,adhesion property and biocompatibility.The obtained fibrous hydrogels show great potential as wound dressing materials,and the study could provide reference value for development of adhesive and stretchable fibrous hydrogels.