Er^sup 3+^ -Doped Y^sub 2^O^sub 3^ Nanophosphors for Near-Infrared Fluorescence Bioimaging Applications

Rare-earth-doped ceramic nanophosphor (RED-CNP) materials are promising near-infrared (NIR) fluorescence bioimaging (FBI) agents that can overcome problems of currently used organic dyes including photobleaching, phototoxicity, and light scattering. Here, we report a NIR-NIR bioimaging system by using NIR emission at 1550 nm under 980 nm excitation which can allow a deeper penetration depth into biological tissues than ultraviolet or visible light excitation. In this study, erbium-doped yttrium oxide nanoparticles (...) with an average particle size of 100 and 500 nm were synthesized by surfactant-assisted homogeneous precipitation method. NIR emission properties of ... were investigated under 980 nm excitation. The surface of ... was electrostatically PEGylated using poly (ethylene glycol)-b-poly(acrylic acid) (PEG-b-PAAc) block copolymer to improve the chemical durability and dispersion stability of ... under physiological conditions. In vitro cytotoxic effects of bare and PEG-b-PAAc-modified ... were investigated by incubation with mouse macrophage cells (J774). Microscopic and macroscopic FBI were demonstrated in vivo by injection of bare or PEG-b-PAAc-modified ... into C57BL/6 mice. The NIR fluorescence images showed that PEG-b-PAAc modification significantly reduced the agglomeration of ... in mice and enhanced the distribution of ... (ProQuest: ... denotes formulae/symbols omitted.)