Synthesis and characterization of pH-sensitive silica nanoparticles for oral-insulin delivery.

The objective of this study is to utilize the pH sensitivity of modified mesoporous silica nanoparticles (MSN) for oral delivery of insulin. Activated silica nanoparticle was modified first with different densities of 3- Chloropropyltrimethoxysilane (3-CTMS) to load the Chlor group which will bond with the organic functional group contained in 4-hydroxybenzoic acid (4-HBA). The nanoparticles were characterized by FTIR and SEM. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). Insulin was entrapped in these nanoparticles and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4). The amount of loading of insulin was increased with increasing -COO- densities resulting from the increasing number of 4-HBA groups. In these cases, the biological activity of insulin was retained. These results were used to design and improve protein release behavior from these carriers.