Preparation of poly acrylic acid grafted-mesoporous silica as pH responsive releasing material

Poly acrylic acid (PAA)-grafted-mesoporous silica (MS) obtained from rice husk ash was investigated for its drug loading and pH-switching release behavior using indigo carmine as a model payload drug. When grafting PAA onto the optimally synthesized MS by UV-irradiation, the grafting efficiency was increased with increasing polymerization time and monomer concentration. Indigo carmine release was less than 10% of that initially loaded into the PAA-g-MS carrier when incubated at pH 2, but at pH 8 the indigo carmine showed a sustained release to >93% after 7.5 h. PAA-g-MS has the potential to be a pH-responsive drug delivery system.