The Fabrication of rGO/(PLL/PASP) @DOX Nanorods with pH-Switch for Photothermal Therapy and Chemotherapy.

The development of well-controlled drug carriers that are stable and highly effective for the delivery of anticancer agents is challenging. Herein, we report a novel pH-controlled drug delivery system, utilizing reducing graphene oxide (rGO)-polymer self-assembly films as carriers, for the preparation of effective drug nanorods and nanoparticles. In this system, the rGO-polymer carriers were constructed by the alternating assembly of poly-l-lysine (PLL) and polyaspartic acid (PASP) around the rGO sheets. Furthermore, the rGO-polymer cores, which possess a positively charged surface as the desired template, could assemble with negatively charged doxorubicin (DOX) via electrostatic interactions. The DOX embedding efficiency and the morphology of the drug nanocomposites could be controlled by the number of rGO-polymer bilayers and concentration of the rGO-polymer bilayers and the initial DOX concentration. Importantly, the release of DOX could be regulated by controlling the pH and by using a NIR laser. Under acidic conditions, the interactions between the PASP layer and DOX molecules can be broken, resulting in gradual release of the DOX molecules. Upon NIR irradiation, the release of DOX could be further accelerated and a photothermal effect from rGO induced. Cellular uptake and cytotoxicity experiments indicate that the drug nanocomposites possess effective anticancer activity. Thus, in this work, we present a useful strategy for the fabrication of pH-responsive drug nanocomposites for combined photothermal and chemical therapy. The nanocomposite can be used as a potential drug delivery system for practical cancer treatment.