NIR Bioimaging: Development of Liposome-Encapsulated, Rare-Earth-Doped Y2O3 Nanoparticles as Fluorescent Probes

Near-infrared (NIR) bioimaging is attracting a lot of attention due to the absence of strong scattering and color fading of the phosphors, which can provide long-term and deep imaging. For fluorescence bioimaging (FBI) in the NIR region, rare-earth-doped ceramic nanoparticles can be one of the best candidates. For the delivery of the ceramic particles to the biological imaging target, liposome-encapsulating the ceramic phosphor is proposed. Liposome-encapsulated, Er-doped Y2O3 nanoparticles were prepared as fluorescent probes for NIR bioimaging. Their surface was modified with PEG, biotin, anionic, and cationic agents. The dispersion, surface charge, and specific interactions of the surface-modified liposomes were characterized. Microscopic and macroscopic NIR bioimages were demonstrated by injecting the liposome-encapsulated, Er-doped Y2O3 nanoparticles into the body of a mouse through the blood vessels. The NIR fluorescence images of the mouse organs are presented.