Construction of Colon-specific Drug Delivery System with pH-dependency 5-ASA Using Grafted CPVA-g-PSSS Microspheres
由CPVA-g-PSSS功能接枝微球构建pH依赖型5-ASA结肠定位释药体系

The graft-polymerization of sodium 4-styrene sulfonate(SSS) was performed on the surface of crosslinked polyvinyl alcohol(CPVA) microspheres with cerium salt-hydroxyl group redox initiation system,the grafted CPVA-g-PSSS microspheres with strong anionic polyelectrolyte PSSS were obtained.On this basis,the adsorption property of the microspheres for 5-amino salicylic acid(5-ASA),namely drug carrying ability,was investigated and the adsorption mechanism analyzed.The in vitro release behavior of the drug-carried microspheres was also examined.The experimental results show that the grafted CPVA-g-PSSS microspheres exhibit very strong adsorption ability for 5-ASA by driving of electrostatic interaction in the acidic medium.Their adsorption capacity can reach 39.1 mg/g,displaying a high efficiency of drug-loading.Their in vitro release behavior is highly pH-dependent.In the medium of pH=1,the drug is not released,while in that of pH=7.4,the burst release occurs,displaying an excellent colon-specific drug delivery behavior.