Facile approach for developing gold nanorods with various aspect ratios for an efficient photothermal treatment of cancer

Abstract

Here, we report a facile preparation of high purity gold nanorods using a cetyl trimethylammonium bromide (CTAB) assisted colloidal approach and functionalization with mercaptoproponic acid. The latter replaces CTAB on the gold nanorod surface, allowing an exceptionally stable aqueous dispersion of the nanorods due to the formation of Au-S bonds. The aspect ratio of the gold nanorods is easily controlled by the reaction time with the maximum of 4.3, allowing absorption in the near-infrared (NIR) region and efficient heat release. This leads to a temperature gradient of 3 °C/min and 42 °C reached for only 6 min in the case of the gold nanorod concentration of 20 μg/mL. The studies of cell viability demonstrated a low cytotoxicity of the gold nanorods with the 4.3 aspect ratio, allowing 92% survival of living cells for 48 h. Furthermore, in mice injected with these nanorods and subjected to NIR-laser irradiation for 10 min, the cancer tumor progressively decreased in volume and fully disappeared within four weeks. A robust fabrication of these gold nanorods with a desirable aspect ratio leading to an efficient heat generation by a NIR laser, makes them exceptionally promising for photothermal ablation of cancer.