Synthesis and tailoring of multifunctional lanthanide nanomaterials for nanomedicne
Date of Issue2012
School of Chemical and Biomedical Engineering
The research work presented in this thesis focuses on the synthesis and tailoring lanthanide nanomaterials for nanomedicine, namely bio-imaging and cancer ablation. Owing to the sharp, intense up-conversion emission in wavelength ranging from ultra-violet to near-infrared, and unique magnetic properties, lanthanide doped nanomaterials have attracted strong research interests in nanomedicine. Ytterbium enriched NaYF4：Yb3+, Er3+/NaDyF4: Yb3+ nanocrystals were first prepared as a powerful dual-mode contrast agent in fluorescence imaging and magnetic resonance imaging (MRI) by rational integration of different lanthanide ions within a single nanocrystal. The “poisonous” effect of Dy3+ on up-conversion emitters Er3+ has been successfully circumvented and the transverse relaxivities of the nanocrystals are much higher than other T2 contrast agents, indicating their suitability as contrast agents in up-conversion fluorescence and MRI. NaDyF4:Yb3+/ NaGdF4:Yb3+, Er3+ nanorods (NRs) were then synthesized. The NRs show excellent dark T2 contrast enhancement due to the presence of Dy3+ ions. Interestingly, tunable positive and negative T1 enhancement can be achieved by using different MRI sequences. They also show good up-conversion fluorescence, which indicate their potential as a new generation dual mode “smart” contrast agents in the area of optical/MRI bimodal imaging. Near-UV and blue up-converting NaYF4:Yb3+, Tm3+ NCs have been optimized and further used to excited CdSe QDs in order to achieve tunable up-converting multicolor emission in core-shell NaYF4:Yb3+, Tm3+-CdSe nanocrystals. These nanocrystals are potential candidates as multicolor probes and contrast agents in imaging, fluorescence-based assay, optical barcodes for identifying analytes in multiplexed assays and chemosensing or biosensing. These nanocrystals open up new avenues as multicolor fluorescence in biolabeling in and biodetection applications.
DRNTU::Engineering::Chemical engineering::Biochemical engineering