Fabrication And Properties Of Novel Composite Crosslinked Chitosan-based Wound Dressings

With the increasing levels of modern medicine, the traditional wound dressing can not meet people’s requirements for different types of wound repair. Developing more effective and comfortable wound dressing which can meet the different circumstances of wound is one of hot research topic in the field of tissue engineering. Chitosan, as a renewable bio-medical materials, has excellent physical, chemical, and medical properties, also with many derivatives. It has accounted for a considerable proportion in the field of wound dressings. It is well known that using chitosan or its derivative alone is hard to satisfy the requirements for different wound repair. For this purpose, a chemical modification and crosslinking method was used to prepare composite cross-linked hydrogel films and composite cross-linked sponges under a mild reaction conditions. After that, we evaluated their potential application as wound dressings.(1) PVA-COOH / CS composite cross-linked hydrogel filmTo prepare the crosslinked hydrogel films, poly(vinyl alcohol)(PVA) was grafted with succinate acid to yield carboxyl-modified poly(vinyl alcohol)(PVA-COOH). 1H NMR and FTIR spectroscopy results show that the target product preparation is successful. Hydrogel films based on PVA-COOH and chitosan(CS) at different concentrations were crosslinked through the formation of amide linkages by EDCI / NHS catalysis. Fourier transform infrared spectroscopy results showed the success of the crosslinking reaction; X- ray diffraction results show that the cross-linking structure resulting in weakening of the molecular crystal; Scanning electron microscopy exhibited that the cross-linked films have a network structure with many holes and pores after swelling and freeze-drying process, which could affect the films’ swelling and mechanical properties. In addition, compared to the blend films, the cross-linked one has a great improvement in mechanical properties. The swelling ratio and gas permeability can be regulated by changing the ratio of the two materials. Cells and blood compatibility test proved that the cross-linked hydrgel film has good biocompatibility, and can effectively promote cell adhesion and proliferation. The drug loaded film exhibits sustained drug release profile, and can effectively suppress bacterial proliferation. The novel cross-linked film show a good application potential as wound dressing.(2) Pullulan-COOH / CMCS composite crosslinked spongeSuccinic anhydride is used to decorate on the pullulan, and 1H NMR and FTIR spectroscopy results show that the pullulan molecular has modified with carboxyl group, which means the target product(Pullulan-COOH) is successfully prepared. A secondary lyophilized crosslinking method was used to prepared Pullulan-COOH / CMCS composite crosslinked sponge in different proportions. Fourier transform infrared spectroscopy was used to characterize the chemical structure after crosslinking. Compared to CMCS sponge, composite crosslinked sponge has a certain upgrade in porosity, probably owing to the increasing of layered structure after crosslinking. The composite crosslinked sponge can absorb a lot of liquid and reach swelling equilibrium quickly, which can reduce the accumulation of wound exudate in a certain degree; WVTR has improved. Biocompatibility test showed the crosslinked sponge had no cytotoxicity or hemolytic potential,which can effectively promote the regeneration process of the skin wound.