Silicon-germanium nanoresonators for optical hyperthermia with simultaneous real-time temperature monitoring in cells

The integration of nanotechnology into medicine has enabled advanced therapeutic strategies, including photothermal therapy (PTT) and light-triggered drug delivery. Central to these modalities is the use of optically active nanoparticles (NPs) capable of converting light into localized heat. While silicon (Si)-based dielectric NPs offer promising biocompatibility and Raman-based nanothermometry, their limited absorption in biological transparency windows hinders the photothermal efficiency. Here, we report the chemical-free laser-assisted synthesis of alloyed all-dielectric Si 1-x Ge x NPs that exhibit dual functionality as efficient nanoheaters and nanoscale thermometers under near-infrared (NIR) irradiation. The all-dielectric composition of the proposed Si 1-x Ge x NPs offers enhanced NIR light-to-heat conversion efficiency and Raman-based nanothermometry empowered by Mie resonances that promote efficient light absorption and confinement, as well as reduced photothermal damage of surrounding tissues due to minimized non-radiative energy dissipation. We performed comprehensive structural, optical, and biological analyses of the Si 1-x Ge x NPs, supported by numerical simulations, to assess the thermal performance, cytotoxicity, internalization, and intracellular heating dynamics in B16-F10 melanoma cells. Compared to pure Mie-resonant Si NPs, the as-synthesized Si–Ge suspensions demonstrated superior light-to-heat conversion at clinically relevant laser power densities while maintaining a favorable safety profile. Our results establish the alloyed Si 1-x Ge x NPs as a promising all-dielectric platform for integrated PTT and temperature-controlled nanomedicine.