Laser-driven synthesis of vacancy-engineered amorphous palladium phosphosulfide quantum dots for high-performance dual-NIR photothermal therapy

Amorphous noble metals exhibit unique electronic properties due to their disordered atomic structures; however, their potential in photothermal therapy (PTT) remains largely unexplored. This limitation arises primarily from difficulties in suppressing crystallization and achieving broadband optical absorption across both near-infrared (NIR) biological windows. Furthermore, direct experimental evidence demonstrating their effectiveness in broadband photothermal applications is scarce. To address these challenges, this study reports, for the first time, the synthesis of amorphous Pd–P–S quantum dots (a-Pd-P-S QDs) featuring engineered phosphorus-sulfur dual vacancies, fabricated via a facile laser ablation in liquid (LAL) method. This efficient physical technique effectively inhibits noble metal crystallization, enabling one-step production of Pd-based quantum dots with exceptional photothermal performance across the NIR-I (650–950 nm) and NIR-II (1000–1350 nm) spectral ranges. The synthesized quantum dots exhibit high photothermal conversion efficiency, excellent photothermal stability, and favorable biocompatibility. Photothermal heating and photothermal cytotoxicity were evaluated under both 808 nm (NIR-I) and 1064 nm (NIR-II) irradiation to substantiate the “Dual-NIR” capability, first in dispersion and then at the cellular level. While in vivo studies, 1064 nm laser was intentionally prioritized to leverage the practical advantages of the NIR-II window for deep-tissue applications. Notably, in vivo studies demonstrate that under 1064 nm laser irradiation at 1.0 W/cm 2 , the BSA/a-Pd-P-S QDs achieve a 91.8% suppression of tumor growth in a murine breast cancer model, with minimal systemic toxicity confirmed by hematological and histopathological analyses. This work not only introduces a universal and environmentally friendly laser-processing approach but also provides, for the first time, mechanistic insights into vacancy engineering within Pd-based quantum dots to enhance photothermal efficacy. These findings advance the development of next-generation deep-tissue theranostic platforms and expand the potential applications in future nanomedicine. • A one-step laser ablation strategy directly yields amorphous Pd–P–S QDs with engineered P/S divacancies from crystalline PdPS. • The amorphous QDs exhibit broadband absorption and high photothermal conversion efficiencies in both NIR-I (77%) and NIR-II (54%) windows. • In vivo photothermal therapy achieves 91.8% tumor growth suppression in a murine breast cancer model under 1064 nm irradiation, with negligible systemic toxicity.