Optical Properties Of Upconversion Nanocrystals/ZnO Nanocompsites And Bioconjugation Of ZnO Nanocompsites With Protein

Fluorescence immunoassay is a standard and significant technique in biology, which has been widely be employed in biomolecular recognition, immunoassay, cellular imaging, DNA sequencing and clinical diagnostics etc. As bioprobes, fluorescent nanocrystals have abilities to provide higher sensitivity and specificity in biomolecular detection than organic dye small-molecules due to several advantages in optical properties of high photostability; without photobleaching; large Stokes shift; narrow band emissions; long fluorescent lifetime, in contrast with conventional organic dye small-molecules. In this thesis, the upconverted luminescent (UCL) nanocrystals and fluorescent nanocomposites were chosen as the subject of investigation, which was focused on the upconversion properties of erbium-doped yttria and zinc oxide nanocrystals, synthesis and characterization of water-soluble ZnO-Au nanocomposites, and bioconjugation of ZnO-Au nanocomposites with protein. The main results are as follows:1. The cubic nanocrystalline Y₂O₃:Er³⁺ particles was obtained using a solution combustion (propellant) synthesis procedure. Upon 488 nm wavelength light excitation, both violet and blue upconverted emissions were observed in the samples. Upon 980 nm wavelength light excitation, however, the violet upconverted emissions are also observed with the occurrence of green and red upconverted emissions. The violet upconverted emisson spectra together with the dependence of integrated...