Epitaxial growth of gold on silver nanoplates for imaging-guided photothermal therapy.

Ag@Au core-shell structure nanoparticles, integrating the good stability of Au and the high surface plasmon resonance property (LSPR) of Ag have been extensively employed for photothermal therapy. Up to now, their sophisticated synthesis still remains a great challenge due to the galvanic replacement effect. Herein, through introduction of Ag, we demonstrated that the Ag@Au core-shell nanoplates were easily synthesized in a galvanic replacement-free fashion with no compromise of heating power. Specifically, through fine-tuning the structure of Ag nanoplates that later served as seeds for the overgrowth of Au, the absorption of resultant nanocrystals can be tailored in ranges from visible to near-infrared. Upon resonant laser irradiation, these Ag@Au nanoplates show the feasibility in photothermally eliminating cancer cells. Furthermore, the high atomic numbers of both Ag and Au elements made the nanoplates promising contrast agents for computed tomography that can be harnessed to guide the tumor ablation. The noticeable regression of the solid tumor, regained body weight, along with the absence of signs indicating inflammation relating the long-term toxicity, all support the promising role of Ag@Au nanoplate as a theranostic agent.