Study on preparation of pH-sensitive drug-loaded microcapsules by interfacial polymerization and its characterization

The pH-sensitive microcapsules were prepared by interfacial polymerization,in which caffeine was used as a model drug and hyperbranched poly L-lysine(HBPL) and terephthaloyl chloride as wall-forming materials.Using statistical analysis of orthogonal experiment,the effects of the emulsifying rate,emulsifying time,protective colloid content and content of emulsifier on the encapsulation efficiency of the microcapsules were discussed.The structure and particle size distribution and surface of microcapsules were characterized.The release behaviours of caffeine in different phosphate buffered saline(PBS) pH were investigated systematically.As a result,caffeine was successfully encapsulated in the wall-forming materials.The resultant microcapsules had the narrow particle size distribution and smooth surface.These drug-loaded microcapsules have shown sensitivity to pH value.