Infrared Photothermal Therapy with Water Soluble Reduced Graphene Oxide: Shape, Size and Reduction Degree Effects

Abstract

In this work, we investigate the effects of lateral size and reduction level of polyethylene glycol (PEG)-modified graphene oxide (GO) nanosheets on the photothermal properties. PEG-modified GO (GO–PEG) and reduced graphene oxide (rGO–PEG) matrices were synthesized through amide bond formation between the carboxyl groups of carboxylated GO and rGO and the amine groups of a PEG linker. We found that the reaction temperature has an important influence on the morphology and size of the pegylated nanostructures. While rGO–PEG formed at 80°C is of nanometer size, the GO–PEG, prepared at room temperature, has needle-like shape with micrometric dimensions. The rGO–PEG matrix was found to be highly soluble under physiological conditions with no aggregation observed even after 6 months of storage. The cytotoxicity of both matrices as well as their photothermal properties to ablate cervical HeLa cancer cells and MDA-MB-231 human breast carcinoma cells were studied. There was no sign of acute toxicity of rGO–PEG for HeLa and MDA-MB-31 cancer cells over a wide concentration range. A complete destruction of the tumor cells could be achieved with a laser power of 6 W cm-2 and a concentration of 60 μg mL-1 of rGO–PEG.