Synthesis And Biomimetic Application Of Multifunctional Rare Earth Conversion Luminescent Nanomaterials

As a kind of multifunctional materials, Lanthanide nanoparticles show rich photoluminescence, magnetism, X-ray attenuation and radioactive properties. To further apply in biomedical field, multifunctionalization of lanthanide nanoparticles should be developed by combination different propertiey into one particle. We designed and synthesized new multifunctional lanthanide upconversion nanophosphors(UCNPs) for bioimaging, including:1. Core-Shell-Shell Na Yb F4:Tm@Ca F2@Na Dy F4 nanocomposites for upconversion/T2-weighted MRI/CT lymphatic imagingA core-shell-shell nanocomposite NaYbF4:Tm@CaF2@NaDyF4 was designed and synthesized. Following surface modification with citrate acid, this nanocomposite was hydrophilic, emitted intense upconversion luminescence(UCL), displayed a high Xray computed tomography(CT) value and excellent r2 relaxivity. These results confirmed that the introduction of a middle Ca F2 layer was necessary as a barrier to reduce cross-relaxation and the surface quenching effect, thus enhancing the UCL of Tm3+. This citrate-modified Na Yb F4:Tm@Ca F2@Na Dy F4 nanocomposite was used as a multi-functional contrast agent for trimodal lymphatic bioimaging with CT, T2-weighted magnetic resonance imaging(MRI), and UCL imaging.2. Cyanine-modified nanosystem with “turn on” upconversion emission for bioimaging in vivo of hypochloriteWe developed a complex nano-probe(UCNPs@PC-Cy820) for upconversion luminescence bioimaging in vivo of hypochlorite, through coating Tm3+ doped upconversion nanoparticles with cyanine-dye Cy820 by phosphatidylcholine. Under 980 nm excitation, the characteristic upconversion emission at 800 nm of UCNPs@PCCy820 was quenched by Cy820. Upon addition of hypochlorite, the absorbation band of Cy820 was gradually reduced, and the emission of Tm3+(λUCL=800 nm) was recovered. Finally, using UCNPs@PC-Cy820 as nanoprobe, detection of hypochlorite was achieved in living mice.