NaYF₄:Sm³⁺/Yb³⁺@NaYF₄:Er³⁺/Yb³⁺ core-shell structured nanocalorifier with optical temperature probe

A core-shell structure with a NaYF₄:Sm³⁺/Yb³⁺ core for photothermal conversion nanocalorifier and a NaYF₄:Er³⁺/Yb³⁺ shell as temperature probe for potential applications in photothermal therapy (PTT) were synthesized by a thermal decomposition technique of rare-earth oleate complexes. The optical temperature reading-out property for the NaYF₄:Sm³⁺/Yb³⁺@NaYF₄:Er³⁺/Yb³⁺ core-shell structure was systematically investigated and it was found that in comparison with pure NaYF₄:Er³⁺/Yb³⁺ particles, the temperature sensing performance of the NaYF₄:Er³⁺/Yb³⁺ shell did not become worse due to the presence of NaYF₄:Sm³⁺/Yb³⁺ core. Furthermore, the photothermal conversion behavior for core-shell nanoparticles was successfully examined by dint of temperature sensing of the NaYF₄:Er³⁺/Yb³⁺ shell, and it was found that an excitation-power-density-dependent temperature increase of up to several tens degrees can be achieved. All the experimental results suggested that the core-shell structure may be an excellent nanocalorifier candidate for advanced temperature-controllable PTT.