Engineered Metallic MoWS2 Nanodots for Photoacoustic Imaging-Guided Photothermal Cancer Theranostics

Ternary transition metal chalcogenides (TTMCs) have emerged as promising photothermal nanomaterials owing to their tunable electronic structures and strong light−matter interactions. However, exploiting phase engineering to tailor the optical energy-conversion properties of TTMCs for biomedical applications remains largely unexplored. Here, we report the fabrication of metallic 1T-phase MoWS2 nanodots through dry ball milling and lithium-intercalation exfoliation of chemical vapor transport-grown 2H-phase MoWS2 crystals. The resulting metallic MoWS2 nanodots, containing 74.8% 1T phase, exhibit broad near-infrared absorption, good colloidal stability, acceptable cytocompatibility, and a high photothermal conversion efficiency of 22.2% under 785 nm irradiation, together with strong photoacoustic contrast. Benefiting from the metallic phase-enabled enhancement of light-to-heat conversion, metallic MoWS2 nanodots achieve efficient photoacoustic imaging-guided photothermal ablation of tumors in vivo with favorable biosafety. Our work suggests that phase engineering can be an effective strategy for optimizing the photothermal and photoacoustic performance of TTMCs to expand their potential applications for cancer phototheranostics.