BACKGROUND & AIMSGold nanoparticles are excellent photon-thermal energy converters. The purpose of this work was to investigate the influence of gold nanoparticles on the photothermalysis of A549 lung tumor cells.MATERIALS & METHODSA549 lung tumor cells were exposed to goat antihuman immunoglobulin (Ig)G-conjugated gold nanospheres (40 nm) and were then imaged under a dark-field microscope. The live cells were then subjected to photoirradiation using a 633-nm laser at different power levels. The viability of tumor cells under laser irradiation was monitored by confocal microscopy using a viability-assay kit.RESULTS & DISCUSSIONThe death rates of A549 lung tumor cells after gold nanoparticle exposure increased significantly under laser irradiation. The maximum initial cell death rate was observed at a laser power level of 3.75 mW, with the initial deactivation rate accelerated by a factor of 6.6 and a total loss of 92% of cell viability.CONCLUSIONThis work demonstrated potential applications of gold nanospheres as both imaging probes and enhancing agents for photothermal therapy of cancer.