Engineering gold nanosheets into bugle-like assemblies for plasmon-enhanced near-infrared oncology treatment

Photothermal tumor therapy (PTT) performance heavily relies on the optical properties of energy transfer materials, and the precise tuning of morphology is key to achieving its performance optimization. Among typical noble metal nanostructures, low-symmetry gold (Au) nanocrystals, with tunable optical properties in the visible and near-infrared regions through their localized surface plasmon resonance (LSPR) properties, are able to efficiently convert absorbed light energy into thermal energy and show unique advantages in photothermal applications. In this study, we present a novel synthesis of gold (Au) nanocrystals with low-symmetry shapes, employing hexamethylenetetramine to induce the rolling of Au nanosheets into cone-like structures, which subsequently evolve into bugle forms. The resulting Au nanobugles exhibit strong plasmonic absorption in the near infrared (NIR-I) region, as evidenced by UV-vis spectra and finite-difference time-domain (FDTD) simulations. By optimizing the shape, size and composition of the nanocrystals, the 81 nm Au nanobugles exhibited a significant temperature increase of 23 °C after 15 minutes of irradiation with an 808 nm laser at a power density of 1 W cm^-2. This demonstrates excellent photothermal conversion efficiency, proving the effectiveness of tumor photothermal therapy. This research demonstrates the effective use of low-symmetry plasmonic nanocrystals in PTT, illuminating pathways toward the rational design of high-performance PTT nanomaterials.