PEGylated Copper Nanowires as a Novel Photothermal Therapy Agent

Metal nanowires are promising for their applications including electrical connectors, transparent conductive electrodes and conductive additives, but the use of metal nanowires as photothermal agents to convert light to heat has yet to be reported. Here we synthesized dispersible polyethylene glycol-coated (PEGylated) copper nanowires (CuNWs) and showed for the first time that PEGylated CuNWs were able to convert near-infrared (NIR, 808 nm) light into heat at a photothermal efficiency of 12.5%. The PEGylated CuNWs exhibited good reusability and enabled rapid temperature rise to >50 degrees C in 6 min by NIR irradiation. The PEGylated CuNWs were flexible and intertwined around the cancer cells, which, upon NIR irradiation, allowed for direct heat transmission to cells and effectively triggered cancer cell ablation in vitro. Intratumoral injection of PEGylated CuNWs into colon tumor-bearing mice and ensuing NIR irradiation for 6 min significantly raised the local temperature to >50 degrees C, induced necrosis, and suppressed tumor growth. Compared with other NIR light absorbing noble metal-based nanomaterials, PEGylated CuNWs are relatively easy to synthesize in both laboratory and large scales using the low cost copper. This study demonstrated the potential of PEGylated CuNWs as a new cost-effective photothermal agent, and paved a new avenue to using CuNWs for cancer therapy.