The Redox Behaviour of Randomly Dispersed Single Walled Carbon Nanotubes both in the Absence and in the Presence of Adsorbed Glucose Oxidase

Abstract

Abstract:The electrochemical behaviour of SWCNTs randomly dispersed on gold and glassy carbon electrode surfaces was characterised via cyclic voltammetry and complex impedance spectroscopy, using the ferri/ferrocyanide couple as a redox active test probe . In subsequent investigations glucose oxidase (GOx) was adsorbed onto the SWCNT ensemble without apparent denaturation of the enzyme. Cyclic voltammetry and potential step chronoamperometry were used to quantify and understand the process of electron transfer between the immobilised protein redox site and the working electrode. The effect of pH on the system was also investigated. In particular, we have shown that, for the calculation of electron transfer rate constants for surfaceimmobilised redox systems, chronoamperometry is preferable to voltammetry, which has been the technique of choice until now.

Nitrogen-doped pyrolytic carbon films as highly electrochemically active electrodes

“…The heterogeneous electron transfer rate constant (k 0 ) gives a quantitative measure of the electron transfer behaviour and this was calculated using the Nicholson method; 45 which has been dealt with in more detail elsewhere. 46 The lack of clear peak definition for the as-grown PyC film precluded the possibility of calculating k 0 for this sample, so sluggish was the electron transfer behaviour. The N-PyC displays highly facile electron transfer with a calculated value of k 0 = 0.044 cm s…”

Diamond nano-wires, a new approach towards next generation electrochemical gene sensor platforms

“…Growth parameters are: microwave power 1200 W which generate a substrate temperature around 900°C, gas pressure 50 Torr, gas flow 400 sccm with 0.6% CH 4 in H 2 . B 2 H 6 , as boron source, is mixed in CH 4 , where the boron/carbon atomic ratio (B/C) was 16,000 ppm. Typically 200 nm thick films have been grown.…”

“…The attractive world of low dimensional systems, together with the fabrication of functional nanostructured arrays will play a major role in the new trend of chemical and biochemical nanotechnology. [3][4][5] Nano-wires can be used for tunable transport of electrons with electronic properties strongly influenced by little perturbations on the surface, for giant surface-to-volume ratio enhancements which are important for chemical/bio-chemical applications, and for generation of well defined molecular patterns on bio-sensor surfaces.…”

Immobilized enzyme–single-wall carbon nanotube composites for amperometric glucose detection at a very low applied potential

“…Deviations from the expected 1st order kinetic response were observed indicating the presence of kinetic dispersion. Application 16 of the Gaussian kinetic model of Albery and co-workers 17 resulted in an assignment of a mean rate constant of 830 s À1 and a spread parameter g of 0.9.…”

“…15 Hence the presence of Nafion while enhancing the discrimination between the Faradaic and Capacitative current contributions associated with the immobilized flavin group, may well result in a large potential drop in the interface region. We have recently shown 16 that the FAD/FADH 2 redox kinetics of this system may be directly probed via potential step chronoamperometry. Deviations from the expected 1st order kinetic response were observed indicating the presence of kinetic dispersion.…”