Fabrication And Applications Of QDs-encoded Fluorescent Microspheres In Biological Fluoroimmunoassay

High quantum yield hydrophilic quantum dots (QDs) have shown its potential applications in luminescence crystal, especially in bio-fluorescence probe. QDs provide robust and stable signal intensity, narrow emission spectra, and the broad emission wavelength which can be turned continuously by changing the size and component of the QD particles. Those ideal properties of QDs have been shown in multicolor imaging for bio-sample and vivo tissue. In the synthesis approaches of quantum dots, the aqueous syntheses are easier controlled, higher repeated, lower cost. It is easily to modify the surface of QDs with different functional groups using the aqueous syntheses. Embedding QDs in the microsphere can prevent QDs loss and breakage via the surface modified process. Furthermore, the nanoparticles can be utilized more widely after combined with appropriate material. Provided with both outstanding properties, QDs-micrisphere can be used in bio-labeling, detection and so on.We report two synthesis approaches of QDs-tagged microsphere, and primary fluorescence immunoassays using the encode microsphere in this paper. The LBL core-shell structure is formed utilizing facilitate the adsorption of QDs on the sphere surface via the electrostatic interaction. The negatively charged hydrophilic CdTe QDs are deposited in alternation with poly (allylamine hydrochloride) (PAH)/ poly (sodium 4-styrensulfonate) (PSS)/PAH polyelectrolyte (PE) multilayers on the surface of polystyrene microspheres. The number of PE3/CdTe QDs layers can be concoled for fluorescence code. The optical properties of the CdTe nanoparticles and CdTe-labelled microspheres were investigated by UV-Visible absorption and luminescence spectroscopy, and fluorescence microscopy and SEM were employed for microscopic identification behavior of the luminescent microspheres. The experiment results demonstrate that QD-labeled microspheres which were fabricated using LBL method, have excellent bioactivity in the of fluoroimmunoassays .QDs-tagged microsphere can be produced by coating QDs with silica in the reverse micro emulsion method. The beads not only retain the optical properties of the original QDs, but also enhance the photochemical stability of QDs with the silica cell. CdTe/SiO2 composite particles have been investigated by UV-Visible absorption and luminescence spectroscopy. With an effective biofunction surface modification, CdTe/SiO2 composite particles can be used widely in a number of biomedical applications.