PREPARATION AND CHARACTERIZATION OF pH/TEMPERATURE SENSITIVE MICROCAPSULES BY INVERSE EMULSION POLYMERIZATION

The pH/temperature sensitive microcapsules were prepared by inverse emulsion polymerization, in which sodium alginate (SA) and N-isopropyl acrylamide (NIPAm) were used as the wall material and pentoxifylline as a model drug. The effects of the emulsifier content on the particle size distribution and drug release property of microcapsules were discussed in detail. The structure, morphology, particle size and its distribution of microcapsules were characterized by Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), Malvern particle size analysis and UV-vis spectrophotometer. The release behavious of pentoxifylline in different phosphate buffered saline (PBS) pH were investigated systematically. The results showed that the resultant microcapsules had narrower particle size distribution, smoother surface and higher drug release amount with the percentage weight of emulsifier being 2.0%. The TEM photograph exhibited that the microcapsules had core and shell structures. The drug-release behavior of pentoxifylline from microcapsules was evaluated as a function of pH/temperature. The results indicated that these drug-loaded microcapsules have shown sensitivity to pH value and temperature.