Fabrication Of Upconversion Nanocomposites And Their Applications In Bio-imaging And Detection

Due to the special photoluminescence process, the upconversion nanophosphors (UCNPs) as nanoprobes have attracted increasing attention in the application of bioimaging and detection.In this thesis, using UCNPs as a core, several functionalized upconversion nanocomposites could be fabricated and further applied in multi-modality bioimaging and detection.1. LiLuF4-based upconversion nanophosphors for dual-modality bio-imaging in vivoLiLuF4 based UCNPs were synthesized using a high boiling solvent process. They had spindle shape and a dimer around 20 nm, of a standard tetragonal structure. In vivo bio-imaging (UCL and X-ray CT) of a whole body Kunming mouse and lymph nodes was realized through vein injection after modifying the nanophosphors’ surface with PEG ligands. All these fact indicated that such LiLuF4-based UCNP was excellent luminescence material for bio-imaging in vivo.2. Iridium Complex-Modified Upconversion Nanophosphors for Effective LRET Detection of Cyanide Anions in Pure WaterWe coated amphiphilic block-polymer onto the surface of hydrophobic OA-coated NaYF4:Yb3+/Ho3+ UCNPs to fabricate a hydrophilic nanostructure. CN--reactive iridium(Ⅲ) complex ([(ppy)2Ir(dmpp)]PF6, Irl) were then loaded to form the nanocomposites. These nanocomposites serve as a probe to detect CN-based on a luminescent resonance energy transfer (LRET) process with UCNPs and Irl as donor and accepter, respectively.3. Fabrication of UCNPs/magnetic Yolk-shell nanocomposites and their applications in detection and removal of Hg2+Here, N719 functionalized magnetic based silica Yolk-shell nanocomposites were synthesized, and their applications in detecting and removal of mercury ions were evaluated by optical titration experiments and ICP. Using the ratiometric absorbance as a detection signal, the detection limit of Hg2+ for this nanoprobe in water was calculated to be 200 ppb. In addition, yolk-shell nanocomposite with core-shell UCNP@SiO2 as core and SiO2 as shell was synthesized.