Preparation And Properties Of Functional Chitosan Hydrogels

Hydrogel is a three-dimensional network polymer with high water absorption and water retention properties,and its expansion ratio can reach hundreds times that of the dry weight of gel.Functional hydrogel is a kind of soft material that can change its performance when the external environment（such as temperature,p H value and pressure）changes.Functional hydrogel is a kind of soft material that realizes its own performance change and responds when the external environment（such as temperature,p H value and pressure）changes.Chitosan has the advantages of environmental friendliness,abundant sources and biocompatibility,and is easily chemically modified.Therefore,functional chitosan hydrogels have become a research hotspot in recent years.The self-healing oxidized sodium alginate-glycol chitosan hydrogel（OSA-GC）based on dynamic imine bonds was synthesized in this study.Oxidized sodium alginate（OSA）was synthesized by oxidizing sodium alginate with sodium periodate,and OSA-GC self-healing hydrogels with different cross-linking degrees were prepared by Schiff base reaction with glycol chitosan（GC）.The results show that OSA-GC hydrogels have the characteristics of porous structure with a pore size ranging from 50 to 280μm,The swelling ratio of OSA-GC hydrogel can reach 71.3～112.1,and the mass loss is43.1%～51.9%after 12 days.At room temperature,OSA-GC hydrogels can achieve self-healing within 2 hours in the absence of external stimuli.OSA-GC hydrogel loaded with gemcitabine show a sustained release effect on the anti-cancer drug gemcitabine,and the release time can reach 48 h in the drug release experiment.In order to improve the gelation concentration of poloxamer temperature-sensitive hydrogel,the poloxamer(P₄₀₇)was used as the substrate,and hexanoyl ethylene glycol chitosan（HGC）was compounded with poloxamer to prepare HGC/P₄₀₇composite hydrogel.The sol-gel transformation can occur in HGC/P₄₀₇hydrogel based on 3%poloxam by controlling the addition of HGC,and the sol-gel transition temperature is between 32 and37℃.The pore size of HGC/P₄₀₇composite hydrogel is in the range of 10-90μm.The drug release amount of HGC/P₄₀₇composite hydrogel is 82%～90.6%,and the sustained release time could reach about 72 h.In this paper,oxidized methyl cellulose（DAMC）was synthesized by periodate oxidation using methyl cellulose（MC）as raw material.DAMC-HGC hydrogels with self-healing and thermo-sensitive properties were synthesized by Schiff base reaction between the aldehyde group of DAMC and the amino group of hexamethylene glycol chitosan（HGC）,and hydrophobic interactions of MC and HGC respectively.The results show that DAMC-HGC hydrogel shows thermo-sensitive sol-gel transition behavior,and can be achieved self-healing within 30 minutes in the absence of external stimuli at 37℃.DAMC-HGC hydrogel have the characteristics of porous structure with a pore size ranging from 30～220μm.The swelling ratio can reach 86.8～139.5.DAMC-HGC hydrogels loaded with gemcitabine show a sustained release effect on the anti-cancer drug gemcitabinee,and the release time can achieve 96 h.The drug release amount of DAMC-HGC hydrogels can reach 72.6%～89.5%.