Molecular Combing of Carbon Nanotubes

Initially, molecular combing was used to comb a nanotube over a pair of gold electrodes. Self-assembled monolayers (SAMs) on the electrodes and the silicon substrate were used to help induce the SWCNT (dispersed via sodium dodecyl sulphate [SDS]) to deposit at the correct location the liquid-air meniscus was then used to orient the nanotube across the two electrodes (Fig. 16.2b). This method has the advantage of being easily scalable. However, contact with the nanotube is superior when the electrode is deposited with e-beam lithography over the nanotube. Because molecular combing is a very convenient way to extend nanotubes on the substrate, it is often used in this case as well. These studies have demonstrated 

The phenomenon of molecular combing of SWCNTs dispersed with SDS was studied further by Ko et a/. They investigated how surface preparation and solution conditions can be used to control the density of nanotubes and demonstrated that, just like DNA, 

A special case arises when DNA is used to disperse SWCNTs. The hybrid nanoparticle is similar to double-stranded DNA (dsDNA) in several ways. AFM observations have suggested that DNA wraps around nanotubes in a helical fashion, forming a tight structure with a diameter of 2 similar to dsDNA this is supported 

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