Lanthanide Doped NaCeF₄ Near Infrared Luminescent Nanoprobes Controlled Synthesis And Bioapplications

In this thesis,we mainly study the controlled synthesis,spectroscopy of lanthanide（Ln3+）ions doped NaCeF₄ nanoprobes,as well as their in vitro bioassay and in vivo bioimaging.The main contents of the study are as follows:（1）Hexagonal phase NaCeF₄:Er/Yb nanocrystals（NCs）were synthesized via high-temperature co-precipitation method.By changing the reaction time at 320℃,the particle sizes can be tuned from 7.1 to 200.6 nm.Moreover,their near-infrared（NIR）spectroscopy properties were systematically investigated.Specifically,the maximum NIR-Ⅱ quantum yield for the NaCeF₄:Er/Yb NCs（200.6±16.5 nm）was determined to be 32.75%,upon excitation at 980 nm with power density of～100 Wcm-2。（2）To make the as-synthesized NaCeF₄:Er/Yb NCs hydrophilic for bioapplications,we removed the surface ligands through an acid treatment.Since Ce³⁺ions in host matrix were exposed on the surface of ligand-free NCs after the acid treatment,H₂O₂ can directly oxidize Ce³⁺ to Ce⁴⁺ through redox reaction.The integrated NIR-Ⅱ emission intensity of NaCeF₄:Er/Yb nanoprobes decreased gradually with the increasing level of H₂O₂.As a result,the concentration of H₂O₂ can be quantified by the NIR-II emission intensity of NaCeF₄:Er/Yb nanoprobes.The highly sensitive response of H₂O₂ allows for the detection of biomarker like uric acid（UA）which can yield H₂O₂ through the UA/uricase reaction.The detection limit of UA was determined to be as low as 25.6 nM。（3）The surface of as-synthesied NaCeF₄:Er/Yb@NaCeF₄ NCs were coated with amphiphilic 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy-（polyethyleneglycol）-2000]（DSPE-PEG2000-COOH）phospholipids（Lipo）.To demonstrate their great capability for noninvasive imaging,in vivo bioimaging experiments were carried out based on the Lipo-modified NaCeF₄:Er/Yb@NaCeF₄ nanoprobes via tail vein injection into mice.After 30 min of blood circulation,images were taken upon excitation at 980 nm（0.2 Wcm-2）with appropriately equipped filters.After injection of 0.5 to 1 h,images of the mouse blood vessel of organs and hindlimb can be clearly observed.