Synthesis and Characterization of Novel pH-sensitive Nano Composites for Oral Drug Delivery

The free-radical graft polymerization of methacrylic acid onto surface activated nano silica particles was studied experimentally. Activated silica nanoparticle were modified using different concentration of 3-Chloropropyltrimethoxysilane (3-CTMS) to load the Chlor group by bonding with the organic functional group contained in 4-hydroxybenzoic acid (4-HBA). The carboxyl group of 4-HBA was then converted to vinyl ester group by reacting nano silica-bound benzoic acid (NSBA) and vinyl acetate as an acylating agent in the presence of catalyst. Methacrylic-type nano composites were synthesized by free radical copolymerization of methacrylic acid and vinyl ester derivative of modified nano silica. The nano composites were characterized by the FTIR and SEM techniques. The equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). Naproxen was entrapped in the as-prepared nano composites and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4).