Lanthanide-doped Nanocrystals: Synthesis And Application In Bioimaging

Due to the special photoluminescence properties, Lanthanide-doped nanocrystals have great potential to be widely used in bioimaging and nanoprobes. But lanthanide-doped nanocrystals themselves have no response to the ions to be detected, they have to be used as a nanocomposite together with organic moleculars. Constructing the nanocomposite of lanthanide-doped nanocrystals and organic moleculars for near infrared nanoprobes in vivo is the hotpot of current research. In this thesis, we design near infrared light excited hypochlorite nanoprobe in vivo, with mesoporous silica shell as the nanocarrier on the surface of lanthanide-doped nanocrystals and organic molecular dye loaded into the mesoporous silica shell. We further detect inflammatory model of small animals with this nanoprobe. Furthermore, we design Nd3+ doped rare-earth downconversion luminescent nanocrystals for photoluminescence and magnetic resonance imaging dual-modal imaging of liver and kidney and lymph node in vivo.1. h Cy5.5-modified upconversion nanosystem for sensitive detection in vivo of HypochloriteHerein, we designed three-layer nanostructure hypochlorite nanoprobe with Er3+, Tm3+ co-doped lanthanide-doped upconversion nanoparticles, mesoporous silica shell and organic molecular dye. We further detected HOCl/Cl O- in living cells and animals. Then arthritis model was established with Kuming mice and the nanomaterial was used to detect arthritis in mouse modal. The nanoprobe was capable of monitoring HOCl/Cl O- in living cells and small animals by UCL bioimaging and ratiometric UCL imaging.2. PEG modified Na YF4:Nd@Na Gd F4 core/shell nanostructure for photoluminescence and MRI dual-modal imagingNd3+ doped lanthanide downconversion nanocrystals have deeper penetration depth and lower thermal effect compare with 980 nm light excited upconversion nanoparticles. We designed Na YF4:Nd downconversion nanocrystals with different Nd3+ doping concentrations. Na Gd F4 matrix was further covered onto the surface of Na YF4:Nd core. The best doping concentration of core/shell structure was chosen through photoluminescence. The core shell Na YF4:Nd@Na Gd F4 nanocrystals were further modified with hydrophilic PEG and then be used for liver and kidney imaging and fluorescent guide lymph node surgery in living mice. For the modification of Na Gd F4 shell, the nanomaterial can be used as MRI imaging contrast agent and realize photoluminescence and MRI dual-modal imaging.