Preparation And Performance Evaluation Of Trichosanthin Polysaccharide/Astragalus Polysaccharide Hydrogel

Diabetic foot ulcer(DFU)which are long duration,hard to cure,high disability rate,affect the quality of life of patients seriously.The hydrogel have been used as a new type of dressing for their good water retention and biocompatibility.At present,the reported hydrogel materials are inactive,so they need to load with various drugs and cells when treating DFU,and these will affect the properties of the hydrogel such as mechanical strength and water retention.Therefore,such hydrogel dressing are not applied in clinical trials.Preparing hydrogels with active function al materials is one of solution.Polysacharides Chinese traditional medicine from are good candidate materials,which have pharmacological activities including regulation of immunity,hypoglycemic and antibacterial action.Hence,we prepared a polysaccharide hydrogel,which make use of hypoglycemia activity and antibacterial activity,and evaluated its performance of traditional Chinese medicinal Snakegourd root/Astragalus polysaccharide by covalent cross-linking and double cross-linking method and characterized them.Covalent cross-linking method was successfully used to prepare Snakegourd root/Astragalus polysaccharide hydrogel.Ultrasonic and water and alcohol were used to extract the Snakegourd root/Astragalus polysaccharides.The polysaccharide(Snakegourd root: Astragalus = 1:3,m/m)was oxidized.Carboxymethylation of chitosan to prepare polysaccharide hydrogels containing different concentrations of N,O-carboxymethyl chitosan(OPCH).The performance evaluation and antibacterial activity of these five hydrogels were studied.The results of microscopic morphology showed that the crude OPCH samples had a clear pore structure with pore sizes ranging from tens to thousands of microns,and mesh-like structures interpenetrated each hydrogel.The pore structure of 2% OPCH~10%OPCH decreases in turn,the pore size gradually decreases,and the tightness of the structure increases sequentially.At the same pH,the swelling rate of OPCH decreased gradually;at pH=1.2,the degradation rate of OPCH increased sequentially;the degradation rate of OPCH decreased in turn at pH 7.4;Rheological experiments showed that the storage modulus of the five hydrogels ranged from 55 to 426 Pa,indicating that the prepared hydrogels had appropriate mechanical strength.The results of antibacterial activity of hydrogels showed that oxidized polysaccharide ofSnakegourd root and Astragalus and Snakegourd root/Astragalus polysaccharide hydrogel had certain inhibitory effects on Escherichia coli and Staphylococcus aureus.The crude extract of Snakegourd root/Astragalus hydrogel in every concentration give more than 80% survival rate of BMSC,as show it is non-toxic to the cells,and polysaccharide hydrogels had a proliferation promoting effect on BMSC.In the experiment,a certain amount of sodium alginate was added on the basis of the Snakegourd root/Astragalus polysaccharide hydrogel prepared by the covalent cross-linking method,and the mixed uniformly was put into a petri dish containing calcium chloride to prepare different OPCH-SA.The performance of the hydrogel was evaluated after five minutes.The results showed that the swelling rate,degradation rate,and water loss rate of OPCH prepared by the double cross-linking method were lower than those of OPCH-SA prepared by the covalent cross-linking method;moreover,the microcosmic morphology showed that the composite Snakegourd root/Astragalus polysaccharide hydrogel prepared by the double cross-linking method had lower porosity,smaller pore size,and tighter structure.Under the same pH condition,the swelling rate of the hydrogel sample gradually decreased;at pH=1.2,the degradation rate of the hydrogel OPCH-SA increased sequentially;on the contrary,the degradation rate of the hydrogel sample decreased sequentially at pH=7.4;the results of rheological experiments showed that the storage modulus of hydrogel prepared by double cross-linking method was 96-131 pa,that is to say,the mechanical strength increased.There was a significant difference in mechanical strength between 2% OPCH and 2% OPCH-SA.Three different types of OPCH-SA of hydrogels prepared by double cross-linking method(2% OPCH-SA,4%OPCH-SA,6% OPCH-SA,8% OPCH-SA,10% OPCH-SA)were printed by a melt-extrusion 3D printer,and bovine serum albumin(BSA)was used as a drug release model to study the effect of shape on the release of protein drugs.The in vitro protein release results showed that in 168 hours,the cumulative release of OPCH-SA to BSA decreased in turn as the concentration of N,O-carboxymethyl chitosan increased,and 2%OPCH-SA to 10%OPCH-SA existed betweens significant differences;the release rate of the circular hydrogel reached at 80.06±0.17% within 7days,and the release rate of the square and rectangular hydrogels did not exceed 60%at pH 1.2;At pH 7.4,the release rate of the circular hydrogel reaches at 89.05±1.13%in 7 days,and the square and rectangular release rate does not exceed 80% yet.In 168 h,there was a significant difference in the release of BSA the three different shapes ofthe OPCH-SA under acidic or alkaline conditions.In summary,Chinese medicinial polysaccharides can be used to prepare different hydrogels by covalent cross-linking and double cross-linking methods.We can control the concentration of carboxymethyl chitosan and the shape of the gel to regulate the release rate of drugs.The results showed that the hydrogel prepared by covalent cross-linking has good biocompatibility and biological activity;the polysaccharide hydrogel prepared by double cross-linking can be processed by 3D printer.