Preparation and swelling property of pH-sensitive calcium alginate porous hydrogel microsphere

Sodium alginate was used to prepare a kind of porous pH-sensitive hydrogel microsphere.Optimum preparation conditions,2wt% sodium alginate,3wt% calcium chloride,gelling temperature of 60℃ and heat preservation time for 40min,were obtained by orthogonal experiment.The swelling ratio of the gel microsphere was 21.8 in pH 7.4 buffer solution(colon pH value environment)for 30min,while it was only 1.5 in deionized water(pH value 6)or pH 1.2 buffer solution(gastric pH value environment)for the same time.The swelling response rate was increased significantly after adding pore former,such as PEG200 and NaCl.The time to swell to the biggest swelling ratio of the gel microsphere was 30 min without pore former in pH 7.4 buffer solution,while the time was 10 min and 15min respectively with appropriate PEG200 and NaCl.