Near infrared triggered dual-functional NaYF4:Yb3+/Tm3+@NaYF4:Yb3+/Sm3+ core-shell UCNPs for temperature sensing and conversion

Upconversion core-shell nanoparticles with dual-function of temperature sensing and photothermal conversion are preferable in diagnose and treatment of cancer. Herein, NaYF4:Tm3+/Yb3+@NaYF4:Sm3+/Yb3+ upconversion nanoparticles have been synthesized by a high-temperature thermal decomposition method. XRD and TEM are used to characterize the crystal structure and morphology of the samples. Temperature dependent upconversion spectra are measured under excitation of 980 nm within the scope of 303-498 K. The investigation on temperature sensing properties are on the basis of the luminescence intensity ratio of Tm3+. The designed core shell nanoparticles and bare core nanoparticles both have good temperature sensing performances, and the sensing properties of both are similar. Furthermore, the photothermal conversion performances are investigated ground on the power dependent temperature measurement, ethanol evaporation experiment and visual infrared thermal images. It is found that the photothermal conversion ability of the core-shell UCNPs is greatly improved by coating of the NaYF4: Sm3+/Yb3+ outer shell.

Automated summary

In this study, upconversion core-shell nanoparticles with dual functions of temperature sensing and photothermal conversion were successfully synthesized using a high-temperature thermal decomposition method. Both the designed core-shell nanoparticles and bare core nanoparticles exhibited similar excellent temperature sensing performances. Furthermore, it was found that the photothermal conversion ability of the core-shell UCNPs was greatly improved by coating with the NaYF4: Sm3+/Yb3+ outer shell.