Study of pH-Responsive and Polyethylene Glycol-Modified Doxorubicin-Loaded Mesoporous Silica Nanoparticles for Drug Delivery.

Tumor-targeted drug delivery systems represent challenging and widely investigated strategies to enhance cancer chemotherapy. In this study, we introduce a novel high-hydrophilic mesoporous silica nanoparticle system with a pH-sensitive drug release. The resultant composite nanoparticles appear as spheres of uniform size (450±25 nm) with a porous structure, which enables a high drug-loading ratio. Through modification of chitosan and polyethylene glycol monomethyl ether, the modified mesoporous silica was non-toxic to normal cells, but effective at inducing tumor cell death. With regard to the characteristics of drug release, the modified mesoporous silica clearly displayed a pH-stimulated release of the model drug doxorubicin hydrochloride in an acidic phosphate buffer solution (pH 4.0 and 6.0). The release was much greater than that observed in neutral or alkaline phosphate buffer solutions (pH 7.3 and 8.0). Furthermore, the release behavior was in accordance with the Higuchi model, indicating that this modified mesoporous silica drug delivery system can exhibit controlled release. The above results imply that the modified mesoporous silica is an effective drug delivery system for cancer therapy.