Antimony Nanopolyhedrons with Tunable Localized Surface Plasmon Resonances for Highly Effective Photoacoustic-Imaging-Guided Synergistic Photothermal/Immunotherapy

Antimony (Sb), a typical group VA semimetal, has rarely been studied both experimentally and theoretically in plasmonic photothermal therapy, possibly due to the lack of effective morphology-controllable methods for the preparation of high-quality Sb nanocrystals. In this study, an effective ligand-guided growth strategy to controllably synthesize Sb nanopolyhedrons (Sb NPHs) with ultrahigh photothermal conversion efficiency (PTCE), good photothermal stability, as well as biocompatibility is presented. Furthermore, the modulation effect of different morphologies on localized surface plasmon resonance (LSPR) of Sb NPHs in experimentation is successfully observed. When the resonance frequency of the Sb NPHs is matched well with the excitation wavelength (808 nm), the PTCE of the Sb NPHs is as high as 62.1%, which is noticeably higher compared to most of the reported photothermal agents. The Sb NPHs also exhibit good photothermal stability. In addition, Sb-NPHs-based multifunctional nanomedicines are further constructed via loading 1-methyl-d-tryptophan on PEGylated Sb NPHs for a highly efficient photoacoustic-imaging-guided synergistic photothermal/immune-therapy of tumors in vivo. This work can stimulate further theoretical and experimental investigations of Sb NPHs and other semimetal nanomaterials regarding their LSPR properties and inspire various potential applications of semimetals in biomedicine and sensors.