Tri-stimuli responsive carbon nanotubes covered by mesoporous silica graft copolymer multifunctional materials for intracellular drug delivery

Abstract

To overcome premature drug leakage and instability in drug delivery systems, we designed tri-stimuli responsive multiwalled carbon nanotubes covered by mesoporous silica graft poly(N-isopropylacrylamide-block-poly(2-(4-formylbenzoyloxy) ethyl methacrylate) multifunctional materials via disulfide linkages (MWCNTs@MSN-s-s-g-PNIPAM-b-PFBEMA). The multifunctional materials could covalently bind and physically load anticancer drug doxorubicin (DOX), and exhibited pH-, temperature- and reductant-induced multi-stimuli responsiveness, significantly enhancing drug loading capacity and improving the release dynamics of drug. The DOX-loaded multifunctional materials exhibited the optimal release behavior in cancer environments compared with in normal cells upon simultaneously triggered by these stimuli. It meant that the MWCNTs@MSN-s-s-g-PNIPAM-b-PFBEMA could serve as efficient gatekeepers to control the mesopore on–off and thus to modulate drug release. The multifunctional materials were proved to be low toxic, whereas the DOX-loaded counterparts had almost the same toxicity as free DOX to cancer cells. Therefore, the developed multifunctional materials can be used as promising drug controlled delivery platforms for cancer therapy.