3D Temperature Mapping During Photothermal Therapy in Cellular Assemblies

Control over temperature in three space dimensions and time is of utmost importance in many contexts, including photothermal therapies, where it is expected to provide valuable insights and enhance clinical outcomes. Current techniques for noncontact temperature mapping during hyperthermia are restricted to 2D imaging, due to the lack of strategies able to provide images in suitable time frames for the inevitable large amount of information encompassed in 3D tomography. Iron selenide nanoparticles (NPs) are developed with high temperature sensitivity that, in combination with low‐field magnetic resonance imaging, enable 3D temperature imaging in the ≈20 s time frame. This approach is suitable for monitoring and evaluating photothermal therapy applied to cellular assemblies, which typically occurs over a time frame of tens of minutes. In addition, iron selenide NPs behave, simultaneously, as photothermal and thermometric agents embedded in cellular models at concentrations where their cytotoxicity is low. This dual functionality enables to control the depth achieved by the therapy with a temperature accuracy ≤1 °C, enabling the detection and control of hot spots that would be otherwise overlooked. Overall, this is a universal approach for temperature mapping in 3D and for localized heating in virtually any living tissue.