Preparation Of Agarose Oligosaccharide Schiff Base Hydrogel And Its Application In Skin Wound Repair

Due to its natural moisturizing properties,hydrogel skin dressings can provide a suitable repair environment for wounds,and have always been favored in the field of skin repair.Natural oligosaccharides are degraded from corresponding natural polysaccharides and have better water solubility and unique biological properties.At present,natural oligosaccharides are mostly used for drug carriers and food additions,and are rarely used as biological materials for the construction of skin repair materials.In this study,the natural polysaccharide agarose with a relatively simple structure was used as the raw material,which was degraded into agar oligosaccharide(AO)with a molecular weight of about 4000 by acid degradation method,and then modified with benzaldehyde groups to prepare aldehydes.Agar oligosaccharide(CBAO),which then reacts with primary amine-containing polymer materials(carboxymethyl chitosan CMCS and hydrazide polyglutamic acid HPGA)to form Schiff base-type dynamic covalent bonds,which in turn form cross-linked networks AO based Schiff base hydrogels were prepared.The structural characterization and physicochemical properties of the hydrogel and its constituent components were studied,and their cytocompatibility,immune activity and antibacterial properties were also evaluated.Possibilities of skin repair.FT-IR and NMR characterizations demonstrated the successful substitution of benzaldehyde groups on AO.When the feed ratio of AO to p-carboxybenzaldehyde was changed from 1:0.5,1:1 to 1:2,the substitution degrees of CBAO were 7.1%,15.4% and 32.7%,respectively.The gel time and rheological tests confirmed that the hydrogel with the best performance was the CBAO/CMCS hydrogel which was mixed with equal volume of CBAO with a concentration of 4% and a degree of substitution of 15.4% and a CMCS aqueous solution with a concentration of 5%..The biocompatibility and bioactivity of CBAO/CMCS and CBAO/HPGA hydrogels were then examined.The results showed that the CBAO/CMCS hydrogel and its components had no obvious cytotoxicity,while the cell viability of the CBAO/HPGA hydrogel was lower than that of the control group.The q PCR test showed that the CBAO/CMCS hydrogel extract was immune inert as a whole;the antibacterial experiment showed that the CBAO/CMCS hydrogel extract had a 40% bacteriostatic rate against Escherichia coli.Finally,the CBAO/CMCS hydrogel was used to carry out the whole-layer damage repair experiment in rats.The results showed that the CBAO/CMCS hydrogel did not cause wound inflammation or hinder wound healing,but also promoted the formation of hair follicles and the appearance of hair at the wound,promoting wound healing.The preparation method of natural oligosaccharide-based hydrogel materials based on dynamic covalent bonds established in this study is expected to be extended to the preparation of various other oligosaccharide-based hydrogel materials and broaden the application scope of natural oligosaccharides.