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@SiO2) 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 SiO2 (QDs@SiO2), the QDs-PDADMAC@SiO2 nanoparticles have much stronger fluorescence, and their fluorescence stability could be obviously improved. Moreover, QDs-PDADMAC@SiO2 exhibits good biological compatibility which promotes their application in cellular imaging.

Graphical abstractThe staining effect of the control group (a), QDs@SiO2 (b) and QDs-PDADMAC@SiO2(c).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The fluorescence intensity of QDs-PDADMAC@SiO2 is stronger than that of QDs@SiO2. ► The fluorescence stability of QDs-PDADMAC@SiO2 is better than that of QDs@SiO2. ► The cytotoxicity of QDs-PDADMAC@SiO2 was lower than that of QDs@SiO2 ► The staining effect of QDs-PDADMAC@SiO2 was much better than that of QDs@SiO2.