Radionuclide (131)I labeled reduced graphene oxide for nuclear imaging guided combined radio- and photothermal therapy of cancer.

Nano-graphene and its derivatives have attracted great attention in biomedicine, including their applications in cancer theranostics. In this work, we develop 131I labeled, polyethylene glycol (PEG) coated reduced nano-graphene oxide (RGO), obtaining 131I-RGO-PEG for nuclear imaging guided combined radiotherapy and photothermal therapy of cancer. Compared with free 131I, 131IRGO- PEG exhibits enhanced cellular uptake and thus improved radio-therapeutic efficacy against cancer cells. As revealed by gamma imaging, efficient tumor accumulation of 131I-RGO-PEG is observed after its intravenous injection. While RGO exhibits strong near-infrared (NIR) absorbance and could induce effective photothermal heating of tumor under NIR light irradiation, 131I is able to emit high-energy X-ray to induce cancer killing as the result of radio ionization effect. By utilizing the combined photothermal therapy and radiotherapy, both of which are delivered by a single agent 131IRGO- PEG, effective elimination of tumors is achieved in our animal tumor model experiments. Toxicology studies further indicate that 131I-RGO-PEG induces no appreciable toxicity to mice at the treatment dose. Our work demonstrates the great promise of combing nuclear medicine and photothermal therapy as a novel therapeutic strategy to realize synergistic efficacy in cancer treatment.