Streptavidin abdsorption on single wall nanotube: Realization of fluorescent nanostructures

Carbon nanotubes (NTs) are undergoing intense investigation to explore their unique morphological, electronic, mechanical, thermal and optical properties. In many cases, to fabricate nanodevices or supramolecular composites capable of taking full advantage of their unique properties, NTs must be attached to other molecules, nanoparticles (NPs) or surfaces. We investigated the adsorption of streptavidin (Str) onto single walled NTs (SWNTs). In particular, our research decorated SWNTs with Str-conjugated ZnS-encased CdSe quantum dots. The resulting NT-Str-QD nanoassembly fully dispersed in physiologic buffer and was visible by conventional fluorescent microscopy. The latter property suggests that using Str as a macromolecular linker avoids energy transfer from semiconducting QDs to the NTs. Therefore, the NT-Str-QD represents a potentially excellent scaffold for constructing intracellular multivalent nanoprobes.