Synthesis,Assembly,Surface Biofunctionalized And Application Of Upconversion Nanoparticles

Lanthanide-doped upconversion nanoparticles(UCNPs) have unique optical properties(anti-Stoke type emission) as they can sequentially absorb two or more low energy nearinfrared photons and emit a higher energy photon in ultraviolet to near-infrared wavelength range. The advantages of UCNPs include narrow emission peak, low interference between the emission peaks, good photo-stability, low biological toxicity, tunable emission peak with different dopants, near-infrared excitation(980 nm and 800 nm) with low tissue damage and good tissue penetration, and low imaging background. UCNPs have attracted many attentions and represent a hot research topic in recent years, yet many challenges remain for their synthesis, bio-modification, assembly, and biosensing/bioimaging applications.In this thesis, the research has been focused on resolving the above-mentioned challenges for UCNPs, which includes four aspects:(1) controlled synthesis of rare earth UCNPs with various particle sizes, morphologies and optical properties;(2) phase transfer and biofunctionalization of UCNPs with poly-histidine peptides to produce monodisperse, high compact, water-soluble and bioactive UCNPs with 100% conversion efficiency;(3) UCNPs coated with TAMRA-modified peptides prepared through phase transfer for luminescence resonance energy transfer(LRET)-based detection of protease activity in vitro and in vivo;(4) DNA-templated assembly of UCNPs and quantum dots(QDs) for the formation of core-shell satellite structures with integrated optical properties of UCNPs and QDs.