Optomagnetic Heater-Thermometer Nanoplatform for Tumor Magnetothermal Therapy with Operando Temperature Feedback

Real-time temperature feedback during hyperthermia enables precise lesion ablation with minimal damage to healthy tissue. However, the lack of on-demand theranostic agents eludes such applications. This study demonstrates <i>in vivo</i> operando temperature monitoring in tumor magnetothermal therapy using an optomagnetic heater-thermometer nanocluster agent. This agent was synthesized via a precise microemulsion-based assembly of lanthanide luminescent nanocrystals and superparamagnetic iron oxide nanoparticles. We show that the lanthanide luminescent nanocrystals within the agents provide temperature-sensitive luminescence lifetime and depth-sensitive luminescence intensity ratio in the second near-infrared biological window (NIR-II), enabling accurate 3D thermographic mapping of tissues with an uncertainty as low as 0.12 °C. Meanwhile, the iron oxide nanoparticles facilitate targeted accumulation in lesions under an oriented magnetic field and act as heating sources under oscillating magnetic fields without interfering with the operando temperature measurements of lanthanide nanothermometers. With spatiotemporally synchronized thermographic imaging, we achieved efficient, programmed, and noninvasive tumor ablation in mice through controlled mild hyperthermia by adjusting the direction and strength of the applied magnetic field. Our proof-of-concept results suggest that this optomagnetic heater-thermometer nanoplatform is promising for high accuracy <i>in vivo</i> magnetic hyperthermia applications.