No abstract

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 facilitate simple optical determination of cluster sizes of CNTs and their manipulation for fabrication of CNT-based devices.

Viruses are exemplary models in nanoassembly for their regular geometries, well characterized surface properties, and nanoscale dimensions. Armed with versatile tools aimed at site-directed mutagenesis to modify the virion's surface, conjugation chemistry for capsid coupling, and manipulation of nanoparticles, we have demonstrated nanoscale assembly of inorganic carbon nanotubes and quantum dots with engineered viruses to produce an intimate array of hybrid structures.

We demonstrate here the utilization of ultrasonication during template-assisted electrodeposition to synthesize high quality one-dimensional nanostructures. Copper sulfide nanorods were synthesized "sonoelectrochemically" to achieve single-crystal nanorods with predominantly single stoichiometric composition (1.0:1.0 Cu:S). Structural characterization by HRTEM, SAD, EDS reveals that nanorods have fully crystalline hexagonal covellite (CuS) structure, which is topotactically intergrown with minor amounts of nanometer size domains of cubic Cu 1.8 S. Nanorods in the range of 50-200 nm in diameter were produced and electrically characterized as p-type semiconductors.