Preparation And Drug Release Behavior Studies Of PH And Temperature Sensitive Starch Hydrogels

Starch is the most abundant carbohydrate in nature, which posses good biocompatibility, non-toxic and biodegradable. In starch molecular chain, there are a large number of alcoholic hydroxyl, which can reacted with a variety of substances to got different properties of modified starch. It's the raw materials of food, medicine, leather, wastewater treatment, paper making, casting, textiles, materials and other industrial, especially in drug research has broad application prospects.In this paper, high degree of substitution of starch, temperature and pH-sensitive starch-MAH/NIPA hydrogel and starch-MAH/DMAEMA hydrogel were prepared using starch, MAH, NIPA and DMAEMA as the raw material. Optimized processes, structure characterization and performance testing were studied. Drug release behavior was investigated through model calculations and analysis, combined with the results of experiments. The mechanisms were also explored. The specific studies were as follows:1. Preparation of high degree substitution of starchHigh degree substitution of starch was prepared by solvent, and the degree of substitution, structure were studied. Through discussion of factors (starch concentration, reaction temperature, time) on the impact of products. Through the orthogonal design, the optimum process was obtained. In addition, the final product was analysised via IR, DSC and 13~C-NMR. The results show that the product prepared by this method posses high degree substitution.2. Preparation and Characterization of starch-MAH/NIPA hydrogelThe temperature and pH sensitive starch-MAH/NIPA hydrogel was synthesized by starch-MAH and N-isopropylacrylamide. The structure characterization and performance testing were studied. In the preparing process, various factors were investigated according to their influences on the morphology, swelling, and drug loading of hydrogel. Through the central composite design– response surface method, the mathematical models of evaluation indicators and impact factors were established, the process were optimized. The hydrogel with optimal performance could obtained when using 8mgBIS, 5ml solution with NIPA and starch-MAH, 25μlAPS and 33μlTEMED, room temperature for 24 hours. The hydrogel which was prepared under the best conditions was characterized and tested. The results showed that the hydrogel posses good swelling properties, temperature and pH sensitivity. 3. Preparation and Characterization of starch-MAH/DMAEMA hydrogelStarch-MAH/DMAEMA hydrogel was prepared, and structure characterization and performance testing were studied. Various factors were investigated according to their influences on the product. Through the central composite design– response surface method, the mathematical models of evaluation indicators and impact factors were established, the process were optimized. The hydrogel which was prepared under the best conditions was also characterized and tested, which showed that the LCST of starch-MAH/DMAEMA hydrogel is around 44℃, higher than starch-MAH/NIPA hydrogel, and also has good pH and temperature sensitivity.4. Explore the in vitro release and doing model calculationsThe in vitro release of drug-loaded starch-MAH/NIPA and starch-MAH/ DMAEMA hydrogel were researched in different pH phosphate buffer. Drug release process was also investigated. Commonly used models in vitro release were fitted. It was found that first order kinetics model can be in line with the release characteristics better. And starch-MAH/NIPA hydrogel showed better pH/temperature sensitivity and sustained release performance. It will provide a theoretical basis and data reference for further research on hydrogel.