Salt-induced aggregation of gold nanoparticles for photoacoustic imaging and photothermal therapy of cancer.

The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT.