Thermo-responsive release from interpenetrating porous silica-poly(N-isopropylacrylamide) hybrid gels

Novel thermo-responsive inorganic-organic hybrid gels were prepared by hybridizing porous silica and poly(N-isopropylacrylamide) gels (PNIPAAm gel). The internal pores of the silica were filled with PNIPAAm gel to give a thermo-responsive drug reservoir. Brilliant blue FCF (BB) was also added to the hybrid gels for release. The BB release rate was faster above the lower critical solution temperature (LCST) of the PNIPAAm gel than below the LCST. When the temperature changed across the LCST, reversible and thermo-responsive release behavior was observed. The transition of the release behavior upon changing the temperature was similar to the behavior of the PNIPAAm gel itself. The BB release rate can be controlled simply by changing the amount of PNIPAAm gel loaded into the silica. (C) 2001 Elsevier Science BY. All fights reserved.