New Preparation Technology And Properties Of Starch-based Medical-oriented Hydrogels

In this paper,an oxidized starch-based hydrogel with excellent biodegradability and bio-compatibility was prepared by one-step microwave-assisted synthesis with oxidized starch,amino acid,xanthan gum and glycolic acid as raw materials,through the interaction of Schiff base reaction and esterification reaction among functional groups,and then its application area was expanded through further mechanical property and morphological structure modifications.The preparation features of milder condition,simple procedure and green materials and product.It is expected to be applied in the biomedical and environmental industries.First,the oxidized starch-amino acid-glycolic acid crosslinked hydrogel was successfully prepared by microwave-assisted technology.A three-dimensional network was constructed by Schiff base and esterification reaction and confirmed ed by FT-IR,UV and SEM analysis.The effects of preparation parameters on the performance of the hydrogel were studied.The optimal preparation parameters were reaction temperature of 70?,microwave power of 525 W and reaction time of 40 minutes.The ratio of oxidized starch:amino acid:glycolic acid=1:0.3:1.75,the prepared hydrogel had a swelling balance ratio of 8.2 and a Young's modulus of 8.90x10~4 Pa,which demonstrated good anti-bacterial capacity and low cytotoxicity.Second,a natural polysaccharide xanthan gum was selected as a structural enhancer and directly added into the system,blending with other raw materials to prepare the xanthan gum/oxidized starch-amino acid-glycolic acid crosslinked hydrogel.FT-IR and SEM analysis verified that the addition of xanthan gum had no significant effect on the basic network structure of the hydrogel.It only filled the voids in the whole structure,making the arrangement of holes more regular,densely distributed and more uniform in size.The optimal dosage of xanthan gum was studied.When the mass of xanthan gum added was 1.8%of the total mass of the system,the prepared hydrogel had a swelling equilibrium ratio of 8.9 and a Young's modulus of 11.09x10~4 Pa.The last,based on the stability of the three-dimensional network of the hydrogel,a porous carbon material with excellent adsorption properties,was prepared by the combination of freeze-drying,carbonization in a nitrogen atmosphere,carbon dioxide activation and grinding.It possessed densely distributed pores with certain continuity by SEM and TEM analysis,similarly to the pore structure of the hydrogel network.Its pores are composed of mainly micropores and mesopores,and the largest pore diameter is about15 nm.It shown excellent adsorption for methyl orange,and the experimental results found that the higher the carbonization temperature,the higher the rate and capacity of methyl orange adsorption.