Homogeneous NaYF4 dual-functioned core-shell nanostructures with NaYF4:Er3+/Yb3+ core as temperature probe and NaYF4:Sm3+/Yb3+ shell as photothermal converter

In recent years, multi-functional nano-structures potentially used as photothermal conversion agents, biomedical imaging platforms, drug delivery carriers and temperature probes have been widely investigated. In this paper, NaYF4:Er3+/Yb3+@NaYF4:Sm3+/Yb3+ core-shell nanoparticles (NPs) which combined the functions of both the photothermal conversion and temperature detection were synthesized. Temperature sensing properties of the core-shell particles were investigated, and it was found that NaYF4:Er3+/Yb3+ self-coating or NaYF4:Sm3+/Yb3+ coating did not cause substantial change in the temperature sensing properties of Er3+. Furthermore, the photothermal conversion was investigated, and it was found that the photothermal conversion can be achieved by the designed core-shell particles. Moreover, the photo-to-heat conversion capacity increases with increasing Yb3+ concentration and 980 nm laser excitation power, which was also verified by the laser-induced ethanol evaporation experiments.