Photothermal Heating and Real-Time In Situ Luminescent Thermometry with Iron Oxide Core-Silica Shell Nano-Objects

In a world increasingly focused on precision and efficiency, achieving reliable nanoscale thermal feedback in nanoparticle-assisted heating presents significant challenges. It requires meticulous control over the morphology of nano-objects and the precise spatial arrangement of the heater and the local temperature probe, both of which are critical for accurate surface temperature readouts. In this work, real-time nanoscale temperature measurements are presented during the nanoparticle-assisted photothermal heating by using new nano-objects consisting of single iron oxide nanoparticles encased in stellate-like silica shells, loaded with a luminescent coordination compound, namely [(Tb/Eu)₉(acac)₁₆(μ₃-OH)₈(μ₄-O)(μ₄-OH)]. These multifunctional nano-objects act as efficient light-triggered nano-heaters and as ratiometric luminescent thermometers operating between 20-65 °C in water with excellent cyclability and good maximum relative thermal sensitivity of 0.75 ± 0.02% °C^-1 at 65 °C and thermal uncertainty of 1 °C. Real-time in situ temperature monitoring via the Tb³⁺/Eu³⁺ luminescence intensity ratio during photothermal heating under 808 nm irradiation demonstrates reproducibility and reliable thermal feedback, highlighting its potential for advanced temperature-responsive applications.