Poly (vinyl alcohol)/SiO2 composite microsphere based on Pickering emulsion and its application in controlled drug release.

In this paper, with W/O Pickering emulsion stabilized by modified SiO(2) nanoparticles as template, PVA/SiO(2) composite microspheres with PVA hydrogel cores and shells of SiO(2) nanoparticles are successfully fabricated through freezing/thawing method. The final structure and constituents of the products are investigated through SEM, FTIR, and TGA. The PVA/SiO(2) composite microspheres obtained are applied as a drug carrier to study their controlled release behaviors and methylene blue is used as a model drug. The effect of PVA concentration, SiO(2) nanoparticle concentration, and freezing/thawing cycles on the morphology of products and release behaviors is studied. All release curves are, respectively, fitted by Monoexponential equation, Higuchi equation, Weibull equation, and Hixson-Crowell equation. Weibull equation is found to give the best fit to the release process. The fitted results prove that the drug release from the PVA/SiO(2) composite microspheres follows Fick diffusion.