(670b) Silica Based pH-Responsive Nanocomposite Nanoparticles As Controlled Drug Release Carriers

Biocompatible drug carriers with the ability of controlled therapeutic agent delivery is a promising way to overcome the limitations of conventional therapies. Among all types of carriers, silica-based nanocomposites emerged as an encouraging candidate because of the biocompatibility, high thermal stability of silica materials. Moreover, silica based pH-responsive nanocomposite materials can be produced by encapsulation of natural or synthetic pH-responsive polymers, such as alginate, chitosan, poly (methacrylic acid) and poly (acrylic acid). In this study, the pH-responsive silica based nanocomposite nanoparticles were made by silica sol-gel method in water in oil microemulsion system with different polymer (alginate, chitosan, etc.) solutions as water droplets. Nano sized particles between 20-80 nm were detected by transmission electron microscopy. Different surface zeta potentials were showed by dynamic light scattering with different silica polymer nanocomposites. Silica-alginate nanocomposites showed negative zeta potential in acidic solution, however, silica-chitosan nanocomposites had positive zeta potential in the same solution. The polymer weight ratio was detected by thermogravimetric analysis. The results showed increased polymer weight ratio with higher concentration polymer solution used in the water in oil microemulsion. Different drug molecules, such as timolol maleate and nadolol, were used to test the release profile of the silica-polymer nanocomposite nanoparticles at different pH buffer solutions. For silica-alginate nanocomposites, more drugs were released at physiological pH solution compared to acidic solution. However, the release profile of silica-chitosan nanocomposites was opposite compared to the silica-alginate one. Consequently, the aim of this study was to investigate the different silica-polymer nanocomposite nanoparticles and tested their pH-responsive controlled release property.