Upconversion nanoparticles@AgBiS2 core-shell nanoparticles with cancer-cell-specific cytotoxicity for combined photothermal and photodynamic therapy of cancers

UCNPs@AgBiS2 core-shell nanoparticles that AgBiS2 coated on the surface of upconversion nanoparticles (UCNPs) was successfully prepared through an ion exchange reaction. The photothermal conversion efficiency of AgBiS2 can be improved from 14.7% to 45% due to the cross relaxation between Nd ions and AgBiS2. The doping concentration of Nd ions played a critical role in the production of reactive oxygen species (ROS) and enhanced the photothermal conversion efficiency. The NaYF4:Yb/Er/Nd@NaYF4:Nd nanoparticles endows strong upconversion emissions when the doped concentration of Nd ions is 1% in the inner core, which excites the AgBiS2 shell to produce ROS for photodynamic therapy (PDT) of cancer cells. As a result, the as-prepared NaYF4:Yb/Er/Nd@NaYF4:Nd@AgBiS2 core-shell nanoparticles showed combined photothermal/photodynamic therapy (PTT/PDT) against malignant tumors. This work provides an alternative near-infrared light-active multimodal nano structures for applications such as fighting against cancers.

Automated summary

In this study, UCNPs@AgBiS2 core-shell nanoparticles were successfully prepared through ion exchange, resulting in improved photothermal conversion efficiency of AgBiS2 due to cross relaxation between Nd ions and AgBiS2. The doping concentration of Nd ions played a critical role in ROS production and enhanced photothermal conversion efficiency. When the doping concentration of Nd ions in the inner core was 1%, NaYF4:Yb/Er/Nd@NaYF4:Nd nanoparticles exhibited strong upconversion emissions, exciting the AgBiS2 shell to generate ROS for photodynamic therapy of cancer cells.