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Carbon nanotube (CNT) based electronic, optical, chemical, and biological devices are in dire need of simple optical microscopy solutions, which can be utilized to image and manipulate CNTs in solution state, many times in biologically relevant aqueous environments. Here, we demonstrate fluorescence visualization of single-walled carbon nanotubes (SWNT) in aqueous solutions using simple light microscopes. For this purpose, stable SWNT dispersions of sodium-dodecyl-sulfonate (SDS) were prepared and mixed with CdSe−ZnS core−shell nanocrystals (quantum-dots (QDs)) functionalized by mercaptoacetic acid. QDs arrange themselves on the sidewalls of SWNTs by virtue of electrostatic interaction between zinc ions in their shell and electronegative oxygen atoms/anions in the sulfonate group of the surfactant, embodying the fluorescence visualization of SWNTs. Transmitted brightfield, SEM, and TEM images also provide clear indication of SWNT sidewalls decorated with these QDs. This visualization technique will facili...

We report the controlled synthesis of multiwalled carbon nanotube−quantum dot (CNT-QD) heterojunctions using the ethylene carbodiimide coupling procedure (EDC). Thiol-stabilized ZnS-capped CdSe quantum dots containing amine terminal groups (QD−NH2) were conjugated with acid-treated multiwalled carbon nanotubes (MWCNT) ranging from 400 nm to 4 μm in length. Scanning and transmission electron microscopy were used to characterize the conjugation process.