SWCNT shortened

Scheme 1.33 Preparation of PS by nitroxide-mediated living free-radical polymerization and its utilization for the functionalization of shortened SWCNTs.

Homopolymer PS and block copolymer poly(tert-butyl acrylate)-b-styrene, prepared by nitroxide-mediated living free-radical polymerization, were utilized for the functionalization of shortened SWCNTs through a radical coupling reaction (Scheme 1.33) [194]. 

Grafting shortened SWCNTs with PEG by microwave-assisted heating allowed for soluble derivatives of SWCNTs, and remarkably enhanced reaction rates were observed compared with conventional heating [240],... 

Figure 14. Scheme of the different steps involved in the fabrication of aligned shortened SWCNT arrays for direct electron transfer of enzymes such as microperoxidase MP-11. From reference 92. 

In a series of studies, Gooding et al. [85,86] investigated the possibility of direct-wiring redox molecules with the electrode surface through shortened SWC-NTs. They suspected that the SWCNTs may plug into redox enzymes such as GOx, where the redox active center is deeply buried within the protein, and thus... 

Control over the electron transfer process has been achieved by binding tetra-thiafulvalene derivatives to shortened SWCNTs through their esterification, using spacers with different length [132]. In this way, a fine-tuned donor acceptor conjugate was produced with successful control over the recombination process, as a functirai of the dmior-acceptor separation. 

The mechanism of MWCNT de-entanglement is expected to be very similar to the one described for SWCNTs, although the initial state is different. Note that if the sonication treatment is too aggressive and/ or lasts too long, it can lead to local damage of the CNT walls, if not to CNT shortening. Local damage deteriorates both electrical and mechanical properties. At the end of the sonication process, a dispersion of mainly individual CNTs with adsorbed surfactant molecules on their surface is obtained. 

In one of the representative work, Patolsky et al. [24] demonstrated the reconstitution of apo-GOx on FAD cofactor electrically contacted to the electrode via single-walled carbon nanotubes (SWCNTs), which act as conductive nanoneedles that electrically wire the enzyme redox-active site to the transducer surface (Fig. 4A). Before immobilisation, the commercially obtained SWCNTs were chemically shortened by treatment with strong acids. The formation of carboxylic (and phenolic) groups at the nanotube ends (and sidewall defect sites) as a result of acid treatment allowed the covalent immobilisation of the SWCNTs on thioethanol/ cysteamine-modified Au electrode in the presence of the coupling reagent 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) as depicted in Fig. 4A. The incorporation of 2-thioethanol in the mixed monolayer prevented... 

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