Mesoporous silica nanotubes coated with multilayered polyelectrolytes for pH-controlled drug release.

Two kinds of inorganic/organic hybrid composites based on mesoporous silica nanotubes (MSNTs) and pH-responsive polyelectrolytes have been developed as pH-controlled drug delivery systems via the layer by layer self-assembly technique. One system was based on alternatively loading poly(allylamine hydrochloride) and sodium poly(styrene sulfonate) onto as-prepared MSNTs to load and release the positively charged drug doxorubicin. The other system was synthesized by alternately coating sodium alginate and chitosan onto amine-functionalized MSNTs, which were used as vehicles for the loading and release of the negatively charged model drug sodium fluorescein. Controlled release of the drug molecules from these delivery systems was achieved by changing the pH value of the release medium. The results of in vitro cell cytotoxicity assays indicated that the cell killing efficacy of the loaded doxorubicin against human fibrosarcoma (HT-1080) and human breast adenocarcinoma (MCF-7) cells was pH dependent. Thus, these hybrid composites could be potentially applicable as pH-controlled drug delivery systems.