Near-infrared light-induced imaging and targeted anti-cancer therapy based on a yolk/shell structure

Abstract

To combine photodynamic therapy (PDT) and bio-imaging for improved antitumor efficacy, we design a yolk-like NaYF₄:Yb,Er@MgSiO₃–ZnPc–RGD mesoporous platform by encapsulating a photosensitive agent (ZnPc) and a targeted peptide, NH₂-Gly-Arg-Gly-Asp-Ser (RGD), into MgSiO₃ mesoporous shell coated NaYF₄:Yb,Er spheres. A novel spinous MgSiO₃ shell is synthesized by an in situ growth process without using any surfactant, instead of the conventional mesoporous silica shell. Upon 980 nm laser irradiation, the emitted red light matches well with the absorbance of ZnPc, which generates reactive oxygen species (ROS) to kill cancer cells, and the retained green light allows for real-time monitoring of the therapeutic process. The in vitro and in vivo results indicate that the platform shows excellent anti-cancer therapeutic efficacy under NIR laser irradiation due to the specialised intracellular transition pattern, avoiding premature leakout of ZnPc, and targeted accumulation in the cancer cell sites. Thus, we envision that our proposed platform should have great potential for PDT-induced tumor therapy and for monitoring biochemical changes taking place in live tumor cells.