Structural symmetry effects in plasmonic metal-semiconductor hybrid heterostructures for multimodal cancer phototheranostics

The structural symmetry is of great importance for optical and chemical behaviors of a complex plasmonic nanostructure system. However, the influence of structural symmetry breaking has been rarely studied in metal–semiconductor heterostructures for cancer phototheranostics. Herein, we present a systematic investigation on cancer phototheranostics of plasmonic Au-Cu 2-x Se nanocrystals (GCS NCs) with different structural symmetries. These GCS NCs are capable of photoacoustic (PA)/computed tomography (CT) diagnostic imaging for tumor visualization and chemodynamic therapy (CDT)/photothermal therapy (PTT) of cancer. We theoretically and experimentally demonstrate much superior near-infrared II (NIR-II) plasmonic and photothermal properties from Janus-GCS NCs because of much stronger plasmonic coupling effects compared with concentric and non-concentric GCS core/shell structures. In addition, more efficient OH production via the combined Fenton-like effects and photocatalytic reaction is evidenced for Janus-GCS NCs with a further enhancement upon the NIR-II laser irradiation. Janus-GCS NCs as a multifunctional theranostic nanoplatform have been demonstrated for highly efficient PA/CT imaging-guided CDT/PTT synergistic cancer therapy in vivo with efficient glutathione depletion. This study highlights the importance of structural symmetry in plasmonic metal–semiconductor heterostructures for cancer phototheranostics.