Selective photothermal ablation of cancer cells by patterned gold nanocages using surface acoustic waves

The patterning of nanoparticles, which are promising photothermal agents, is of great importance to selectively and precisely ablate tissues by thermal effects. In this paper, we demonstrated that nano-sized gold particles (gold nanocages, AuNCS) with a hollow structure could be used to generate various wavefront patterns of surface acoustic waves (SAWs) and the aligned AuNC lines facilitated the destruction of cancer cells by the thermal effect with high spatial resolution. The hollow structure improved the acoustic sensitivity of AuNCs, making them more sensitive to the acoustic radiation force. Moreover, the multi-scale patterning of AuNCs could be achieved by the interference of multiple acoustic beams. Given the photothermal characteristics of AuNCs, selective temperature elevation within a micrometer-sized region could be realized when the patterned AuNCs were irradiated by a laser. The cancer cells where the patterned AuNCs were located were eliminated by thermal ablation, while other cells remained alive. In particular, the acoustic frequency used in this study was as low as 11. 35 MHz and was in the range of diagnostic ultrasound (less than 12 MHz), offering a potential to serve as a powerful tool in clinical applications.