The traditional drug delivery systems always suffer from the unexpected drug release during circulation and the sluggish release of drug in target site. To address the problem, an "off-on" type drug delivery system with precise control was developed in this study. Doxorubicin (DOX) was covalently conjugated to fullerene (C60) nanoaggregates via a reactive oxygen species (ROS)-sensitive thioketal linker (C60-DOX NPs), and then the hydrophilic shell (Distearoyl-sn-glycero-3-phosphoethanolamine-PEG-CNGRCK2HK3HK11, DSPE-PEG-NGR) was attached to the outer surface of C60-DOX, giving it (C60-DOX-NGR NP) excellent stability in physiological solutions and active tumor-targeting capacity. C60-DOX-NGR NPs were able to entrap DOX efficiently even at acidic environment (pH5.5) when they were "off" state. In sharp contrast, when the NPs were "on" state, a large number of ROS were generated by C60, leading to the breaking of ROS-sensitive linker, thereby enabling the burst release of DOX. The "off" or "on" state of C60-DOX-NGR NPs could be precisely remote-controlled by a 532nm laser (at a low power density) with a high spatial/temporal resolution. In the in vivo and in vitro studies, the C60-based drug delivery system with "off-on" state exhibited a high antitumor efficacy and a low toxicity to normal tissues due to its tumor-targeting ability, remote-controlled drug release property and combined therapeutic effect (photodynamic therapy combined with chemotherapy).
Keywords: Fullerene (C(60)); Nanomedicine; One-demand drug release; Photodynamic-chemotherapy; ROS-manipulated drug release.
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