Upconversion NaLuF4 fluorescent nanoprobes for jellyfish cell imaging and irritation assessment of organic dyes

Abstract

Upconversion NaLuF₄ nanoparticles (UCNPs) with intense visible fluorescence and good biocompatibility were successfully synthesized by the solvothermal method and subsequent surface modification, of which the upconversion emission can be tuned by Zn²⁺ doping. These UC fluorescent nanoprobes with oleic acid–PEG hybrid ligands can efficiently capture Rhodamine B (RhB) and sodium fluorescein (SF) in jellyfish to image their excretion in vivo and simultaneously present background-free cell morphologies and efficient luminescence resonant energy transfer (LRET) processes. The irritation of RhB and SF is assessed in jellyfish cells using NaLuF₄ nanoparticles as probes and based on the combination of cell fluorescent imaging with emission spectra from LRET processes. It is clearly determined that RhB presents recoverable physical injury to the cells and SF presents unrecoverable biochemical injury to the cells. This procedure, based on surface controlled UCNPs and the LRET process, supplies background-free imaging and spectrum signals, so that the detecting limitations of conventional ultraviolet excitation are overcome and rapid optical detection of trace organic dyes becomes possible.