Multifunctional polyphosphazene-coated multi-walled carbon nanotubes for the synergistic treatment of redox-responsive chemotherapy and effective photothermal therapy

It is a long-pursued goal to improve the antitumor efficiency while decreasing the systemic side effects of therapeutic agents of cancers. In this study, a multifunctional drug delivery system (DDS) for chemo-photothermal therapeutics was developed by coating an anticancer-drug-containing polyphosphazene (PPZ) onto multi-walled carbon nanotubes (MWNTs) via one-pot in situ polymerization of doxorubicin (DOX) and bis-(4-hydroxyphenyl)disulfide (HPS) with hexachlorocyclotriphosphazene. The DOX loading ratio and release rate were precisely tuned via the adjustment of the DOX to HPS molar ratio. MWNTs were used as a nano-template and near-infrared photothermal conversion agent for effective photothermal therapy. Remarkably, this multifunctional DDS selectively suppressed and killed cancer cells, but negligibly affected normal cells. Hence, this DDS demonstrates the proof-ofconcept for effective chemo-photothermal synergistic therapy.