Chitosan-Capped Mesoporous Silica Nanoparticles as pH-Responsive Nanocarriers for Controlled Drug Release

Herein, we present a straight- forward synthesis of pH-responsive chi- tosan-capped mesoporous silica nano- particles (MSNs). These MCM-41-type MSNs could be used as nanocapsules to accommodate guest molecules. Sub- sequently, (3-glycidyloxypropyl)trime- thoxysilane was grafted onto the sur- face of the MSNs, which served as a bridge to link between MSNs and chitosan, which is ubiquitous in nature and commercially available. Owing to the pH-responsive and biocompatible features of chitosan, the loading and release of an anti-cancer drug, doxoru- bicin hydrochloride, were carried out in vitro, in which the composite chitosan- capped MSNs (CS-MSNs) showed ex- cellent environmental response. As the pH value of the media decreased, the degree of drug release correspondingly increased. Moreover, thanks to the per- fect biocompatibility of chitosan, the CS-MSNs exhibited lower cytotoxicity than that of the naked MSNs in an MTT assay. In addition, the in vitro kill potency against MCF-7 breast-cancer cells was enhanced over time, as well as with increasing concentration of the drug-loaded CS-MSNs. These results indicate that CS-MSNs are promising candidates for pH-responsive drug de- livery in cancer therapy.