Fine-tuning the LSPR response of gold nanorod-polyaniline core-shell nanoparticles with high photothermal efficiency for cancer cell ablation.

Gold nanorods (GNRs) with suitable aspect ratios have strong localized surface plasmon resonance (LSPR) absorption and scattering in the 650-900 nm near-infrared region, which make them attractive for in vitro or in vivo imaging and photothermal cancer therapy. However, they often suffer from cytotoxicity and instability for practical applications, and therefore need further surface modification to solve these issues. In this study, GNRs coated with biocompatible polyaniline (PANI) were used as a stable and highly efficient photothermal agent for cancer cell ablation. Fine-tuning the LSPR response of the GNR-PANI core-shell nanoparticles via thickness-controlled coating of the PANI nanoshells, optimizes the photothermal conversion efficiency of the agent. As a result of the contributions from the GNR core and PANI shell, the capability of photothermal transduction of the resultant nanoparticles at 808 nm is greatly enhanced. After exposure to a continuous NIR laser at 808 nm for ∼5 min, cancer cells were efficiently ablated requiring only a very low laser flux of 0.6 W cm, the lowest value reported to date for plasmonic nanostructures, showing the great potential for photothermal cancer therapy.