Ferrocene-functionalized core–shell lanthanide-doped upconversion nanoparticles: NIR light promoted chemodynamic therapy and luminescence imaging of solid tumors

In the current study, we successfully prepared core–shell NaYF4:Yb,[email protected]4:Eu upconversion nanoparticles to achieve three intense upconversion emissions, the 476 nm emission can active photo-Fenton reaction to introduce the cancer cell apoptosis, while 647 nm and 696 nm emissions are suitable for the upconversion luminescence (UCL) imaging. Nanosystem Lipo-FNPs was then constructed by loading carboxyl-containing ferrocene derivative Fc onto NaYF4:Yb,[email protected]4:Eu UCNPs surface, then further be encapsulated in liposomes. Lipo-FNPs exhibited obvious 980 nm NIR-promoted cytotoxicity induced by ·OH from photo-Fenton reaction, with IC50 = 22.54 ± 1.93 μg/mL in AGS cancer cells. The oxidation product Fc+NPs of photo-Fenton reaction can be reversibly reduced by GSH, which suggested that FNPs have the potential to disturb the intracellular redox homeostasis. Cell fluorescence confocal experiments and in vivo fluorescence imaging experiments confirmed that this nanosystem can achieve biological UCL imaging from cells to the level of living organisms. Therefore, Lipo-FNPs nanosystem was developed to achieve the integrated missions in solid tumors, NIR promoted effective tumor suppression and bright UCL imaging.