Sustained Drug Release on Temperature-responsive Polymer Hybrid Nanoporous Silica Composites

Abstract

Received April 12, 2004 orthosilicate (TEOS) was added into the solution at 40 °C. The mixture was aged in a bomb at 120 °C overnight without stirring. The solid product was filtered, washed with excess water, and air-dried at room temperature. Calcination was carried out at 550 °C for 6 hours. The PNIPAm hybridized nanoporous materials were prepared by the radical-initiated polymerization with NIPAm monomers and 2,2'-azobis(isobutyronitrile) (AIBN) with ammonium sulfate on (3-(methacryloyloxy)propyl)trimethoxysilane (3-MOP) modified nanoporous silica surface after modification of MOP on ordered nanoporous silicas with different pore sizes (10, 17, 30 nm) synthesized (Scheme 1). The dried PNIPAm hybrid nanoporous materials were immersed in a saturated solution of indomethacin in EtOH-water (8 : 2, v/v) over- night and dried over a period of 3 days at room temperature. The drug-loaded composites of the PNIPAm hybrid nano- porous silicas were immersed in 10 mL of phosphate buffer (PBS, pH 7.4, 10 mM). Solutions containing the drug-loaded composites were shaken in temperature-controlled shaker for stepwise temperature changes between 25 °C and 40 °C. The indomethacin concentration of the solution was measured using a UV-Vis. spectrophotometer (257 nm) at