Preparation of strongly fluorescent silica nanoparticles of polyelectrolyte-protected cadmium telluride quantum dots and their application to cell toxicity and imaging.

Based on the polyelectrolyte-protected CdTe quantum dots (QDs), which were prepared by self-assembling of QDs and poly-diallyldimethylammonium chloride (PDADMAC) in the help of electrostatic attraction, the strong fluorescence silica nanoparticles (QDs-PDADMAC@SiO(2)) have been prepared via a water-in-oil reverse microemulsion method. Transmission electron microscopy and Zeta potential analysis were used to characterize the as-prepared nanoparticles. All of the particles were almost spherical and there is a uniform distribution of the particle size with the average diameter about 25 nm. There is a large Zeta potential of -35.07 mV which is necessary for good monodispersity of nanoparticles solution. As compared with the QDs coated by SiO(2) (QDs@SiO(2)), the QDs-PDADMAC@SiO(2) nanoparticles have much stronger fluorescence, and their fluorescence stability could be obviously improved. Moreover, QDs-PDADMAC@SiO(2) exhibits good biological compatibility which promotes their application in cellular imaging.