Preparation of Theophylline Surface Imprinted Microsphere and Its in vitro Drug Release Performance

The molecular surface imprinted microspheres MIP-PSSS/CPVA were prepared using ceriumsalt-hydroxyl group redox initiation system on crosslinked polyvinyl alcohol (CPVA) microspheres, with sodium 4-styrene sulfonate (SSS) as functional monomer, theophylline (TP) as template molecule and N, N′-methylene bisacrylamide (MBA) as crosslinking agent. The MIP-PSSS/CPVA microspheres were further characterized by FT-IR, scanning electron microscope. The combining characteristic of MIP-PSSS/CPVA was studied with static method and the in vitro release behavior of drug-loaded microspheres was explored. Results show that MIP-PSSS/CPVA microsphere has excellent recognition selectivity and combine affinity for the template molecules of TP, which exhibits very strong binding ability for TP, and the binding capacity reaches 92 mg/g at pH=1. TP does not be released in simulated gastric fluid, and the drug cumulative release rate is only 21% in the simulated small intestine fluid for 2~6 h. Whereas, in the simulated colon fluid, an abrupt release will be firstly produced and then drug release is sustained and slowed, displaying an excellent pH and time-delayed double sensitive colon-specific drug release behavior.