Solubilization, SWCNTs

Wang et al. [55] have reported on the ability of the perfluorosulfonated polymer Nafion to solubilize SWCNTs and MWCNTs. They proposed that a homogeneous, well-distributed solution of Nafion/CNTs was obtained with 0.5 % v/v (in 0.05 M phosphate buffer pH 7.4) and 5% v/v polymer solution for SWCNTs and MWCNTs, respectively. A polished GCE was modified with 20 pL of a 2 mg/mL CNTs solution in 0.5 % w/w Nafion. The coating was allowed to... 

Along with the development of CNT electrodes through modification of conventional electrodes by CNTs with and without chemical modification, CNT composite electrodes have been investigated for biosensing applications. For instance, Hrapovic et al. reported that electrochanical sensors made of SWCNTs mixed with 2-3 nm small platinum nanoparticles displayed a remarkably improved sensitivity toward hydrogen peroxide. In this study, Nation, a perfluorosulfonated polymer, was used to solubilize SWCNTs and interact with Pt nanoparticles to form a network that connected Pt nanoparticles to the nanotube electrode surface (Figure 6.10A). 

Sidewalls of CNTs were coated with PEG [241], preventing the nonspecific adsorption of proteins [242, 243], The polymeric layer was subsequently used as an interface for the specific coupling or affinity binding of proteins [242]. By a diamine-terminated oligomeric PEG functionalization, the solubilization of as-prepared and purified SWCNTs was achieved [244], The soluble tubes were characterized by spectroscopic, microscopic and gravimetric techniques. 

These examples of functionalization of carbon nanotubes demonstrate that the chemistry of this new class of molecules represents a promising field within nanochemistry. Functionalization provides for the potential for the manipulation of their unique properties, which can be tuned and coupled with those of other classes of materials. The surface chemistry of SWCNTs allows for dispersibility, purification, solubilization, biocompatibility and separation of these nanostructures. Additionally, derivatization allows for site-selective nanochemistry applications such as self-assembly, shows potential as catalytic supports, biological transport vesicles, demonstrates novel charge-transfer properties and allows the construction of functional nanoarchitectures, nanocomposites and nanocircuits. 

Nonsilicate-carbon nanotube composites were also reported by the same group [221]. They reported that a SnO-CNT anode showed improved lithium intercalation properties compared to the respective CNT and tin oxide electrodes. Wang et al. showed that Nation addition can solubilize CNTs in neutral-pH phosphate-buffered aqueous and alcohol solutions [222], Soon afterward, titania-MWCNT andmesopo-rous titania-Nafion-SWCNT and MWCNT electrodes were reported [223,224]. 

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