Magnetic Iron Oxide Nanoparticles Coated by Coumarin-Bound Copolymer for Enhanced Magneto- and Photothermal Heating...

In this work, we report on the synthesis and investigation of new hybrid multifunctional iron oxide nanoparticles (IONPs) coated by coumarin-bound copolymer, which combine magneto- or photothermal heating with luminescent thermometry. A series of amphiphilic block copolymers, including Coum-C₁₁-PPhOx₂₇-PMOx₅₉ and Coum-C₁₁-PButOx₈-PMOx₄₂ bearing luminescent and photodimerizable coumarin moiety, as well as coumarin-free PPhOx₂₇-PMOx₅₇, were evaluated for their utility as luminescent thermometers and for encapsulating spherical 26 nm IONPs. The obtained IONP@Coum-C₁₁-PPhOx₂₇-PMOx₅₉ nano-objects are perfectly dispersible in water and able to provide macroscopic heating remotely triggered by an alternating current magnetic field (AMF) with a specific absorption rate (SAR) value of 240 W.g^-1 or laser irradiation with a photothermal conversion efficiency of η = 68%. On the other hand, they exhibit temperature-dependent emission of coumarin offering the function of luminescent thermometer, which operates in the visible region between 20 °C and 60 °C in water displaying a maximal relative thermal sensitivity (S_r) of 1.53%·°C^-1 at 60 °C.