A large-inner-diameter multi-walled carbon nanotube-based dual-drug delivery system with pH-sensitive release properties.

A novel dual-drug delivery system (DDDS) for cancer chemotherapy has been established by employing highly purified and mildly oxidized large-inner-diameter multi-walled carbon nanotubes (LID-MWCNTs) as the vector. The LID-MWCNTs were modified with the antitumor drugs, cisplatin (CDDP) and doxorubicin (DOX). CDDP was encapsulated inside the nanotube vectors by a wet-chemical approach while DOX was attached to the external surfaces through non-covalently interaction. The loading efficiencies of CDDP and DOX were as high as 84.56 and 192.67%, respectively. Notably, after CDDP was encapsulated inside the nanotubes, a three-level blocking strategy, which included polyethylene glycol, folic acid and DOX, was employed to block the CDDP exits at different levels. The pH-sensitive release profile of CDDP was demonstrated using a modified characterization method, as well as that of DOX. Finally, the anticancer activity of the DDDS on MCF-7 cells was tested and a synergistic effect was recorded. This work is part of our LID-MWCNTs based drug delivery system studies, and provides a basis for developing a novel comprehensive antitumor treatment that combines chemotherapy and photothermal therapy.