Efficient assembly of multi-walled carbon nanotube-CdSe/ZnS quantum dot hybrids with high biocompatibility and fluorescence property

CdSe/ZnS core–shell quantum dots (QDs) were efficiently tethered onto polyamidoamine dendrimer-modified multi-walled carbon nanotubes (MWCNTs) by covalent linkage and mercapto-mediated assembly. The obtained MWCNT-QD hybrids were both photophysically and morphologically characterized. The QDs are well-distributed on single nanotube surface in high density and the assembly of QDs onto MWCNTs does not change the fluorescence emission wavelength of QDs but significantly decreases the emission density. Cytotoxicity of MWCNT-QD hybrids to HeLa cells and their fluorescence property in living cell system were evaluated in detail. The hybrids show a little effect on cell viability even at very high concentration (100 μg mL−1). Moreover, they possess intense red fluorescence signal under optical fluorescence microscopy and good fluorescence stability over 72-h exposure in living cell system.