Upconversion NaYF4:Yb3+/Er3+@silica-TPGS Bio-Nano Complexes: Synthesis, Characterization, and In Vitro Tests for Labeling Cancer Cells.

Fluorescence imaging is an important technique used for early diagnosis and effective treatment of some incurable diseases including cancer. Herein, we report novel NaYF4:Yb3+/Er3+@silica-TPGS bio-nano complexes for labeling cancer cells. The NaYF4:Yb3+/Er3+ nanoparticles have been successfully synthesized via a hydrothermal route, further coated with a silica shell, and functionalized with d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). The experimental results indicate that NaYF4:Yb3+/Er3+@silica-TPGS emits stronger upconversion luminescence than NaYF4:Yb3+/Er3+ under an excitation of 980 nm. More significantly, the NaYF4:Yb3+/Er3+@silica-TPGS bio-nano complexes could strongly label MCF-7 breast cancer cells for in vitro experiments detected by a fluorescence microscope. On the other hand, the complex could not typically probe healthy cells, which are HEK-293A human embryonic kidney cells, under the same experimental conditions. Because of their strong upconversion luminescence, good dispersibility, and biocompatibility, NaYF4:Yb3+/Er3+@silica-TPGS bio-nano complexes can be a promising candidate/probe for biomedical labeling and diagnostics.