Preparation And Properties Of Chitosan-based Natural Polysaccharide Composite Hydrogels

Natural polysaccharides have good biocompatibility,environmental friendliness,regenerability,and biodegradability,which have attracted wide attention in the field of biomedicine.The hydrogel has a three-dimensional network structure,is capable of absorbing and retaining a large amount of water,has a soft and moist surface,and is similar in morphology to the extracellular matrix of a living tissue,and can be used as an ideal material in the field of biomedicine.In this article,three natural polysaccharides,chitosan?CS?,konjac glucomannan?KGM?and hyaluronic acid?HA?,were used as raw materials to prepare novel composite hydrogels which have excellent physical and chemical properties,good biocompatibility,and can promote wound healing and prevent scar formation.The structure of the composite hydrogels was characterized by transform infrared spectroscopy,nuclear magnetic resonance spectrum,X-ray diffraction and scanning electron microscopy.A series of performance tests also were carried out to investigate the physicochemical properties and biological properties of the composite hydrogels to lay the foundation for studies on new hydrogels medical dressings.The main research contents and results are as follows:?1?Carboxymethyl chitosan?CMCS?was prepared by using CS as raw material.MTGase was used as biocatalyst to graft collagen peptide?COP?onto CMCS to obtain CMCS/COP composite and a series of structural characterization and performance tests were carried out for CMCS/COP composite.The degree of carboxymethyl substitution of CMCS was determined to be 0.84,and the degree of substitution of COP in CMCS/COP was 0.36.The results of cell experiments showed that CMCS had good biocompatibility to NS-FB cells and inhibited the proliferation of HS-FB cells;CMCS/COP could promote the proliferation of NS-FB cells and had little effect on the proliferation of HS-FB cells.?2?Oxidized hyaluronic acid?OHA?was prepared by oxidation of HA with NaIO₄ as oxidant,and CMCS/COP/OHA composite hydrogels were prepared by reacting OHA as cross-linking agents with CMCS/COP through Schiff base reaction.A series of structural characterization and performance tests were carried out for CMCS/COP/OHA hydrogels.The results showed that the CMCS/COP/OHA composite hydrogels have a continuous and stable three-dimensional structure,suitable gel time,excellent swelling performance?the maximum swelling ratio was1600%?,well water retention capacity?30%moisture after 24 h?and good blood compatibility.In addition,cell experiments showed that CMCS/COP/OHA hydrogels can promote the proliferation of NS-FB cells and inhibit the proliferation of HS-FB cells.?3?Oxidized konjac glucomannan?OKGM?was prepared by oxidation of KGM with NaIO₄ as oxidant,and CMCS/COP/OKGM composite hydrogels were prepared by reacting OKGM as cross-linking agents with CMCS/COP through Schiff base reaction.A series of structural characterization and performance tests were carried out for the composite hydrogels.The results showed that the CMCS/COP/OKGM composite hydrogels have a continuous and stable three-dimensional structure,short gel time,good swelling performance,good water retention capacity and excellent blood compatibility.In addition,cell experiments showed that CMCS/COP/OKGM composite hydrogels can promote the proliferation of NS-FB cells,and has no obvious side effects on HS-FB cells.?4?The deep second degree scald model of SD rats were prepared.The materials prepared above were used for animal experiments.The effects of materials on the healing of burn wounds were investigated by gross wound observation,wound healing rate,wound healing time and optical microscopy.The results showed these materials can significantly reduce the inflammatory response,promote the formation and growth of capillary and fibroblasts,and facilitate the formation of connective tissue,thereby promoting wound healing.Among them,the composite hydrogels group had the best healing effect,and it had basically healed on the 15th day after the burn,and the CMCS/COP/OHA composite hydrogels group could achieve the effect of weakening scar.