Low potential thiocholine oxidation at carbon nanotube-ionic liquid gel sensor

Ultrasensitive Biosensor for Detection of Organophosphorus Pesticides Based on a Macrocycle Complex/Carbon Nanotubes Composite and 1-Methyl-3-octylimidazolium Tetrafluoroborate as Binder Compound

“…This figure shows plots constructed from the chronoamperograms (inset of Fig. 4), in the absence and presence of ATCh, and the average kobs value calculated from the slope (3.67 × 103 mol -1 L s -1 ) was higher than, or similar to, the obtained for other types of electrodes employed for TCh detection, 14,29 indicating that the composite based on CoTSPc/CNT/OMIM[BF4] presented excellent electrocatalytic properties in terms of TCh oxidation.…”

“…Furthermore, the presence of the ionic liquid (OMIM[BF4]) can accelerate the electron-transfer kinetics of TCh oxidation due to the electrostatic interaction at pH 8.0 (the optimum pH for AChE) between negatively charged TCh and the imidazolium cation. 29 The enzymatically formed TCh can be electrochemically oxidized at a low applied potential (0.0 V). The coupling of the enzymatic oxidation of TCh and the electrochemical reduction of CoTSPc forms a reaction cycle, which results in amplification of the signal.…”

Nanocarbon electrode prepared from oppositely charged nanoparticles and nanotubes for low-potential thiocholine oxidation

“…The shape of the voltammograms and the oxidation peak position are pH dependent (Fig. 6) indicating that protons are involved in TC oxidation to dithiobis(choline) [30]: 2 RSH ! RS-SR + 2e À + 2H + (1) There are two possible mechanisms of TC oxidation [38].…”

“…The first one includes oxidation of protonated TC form, following deprotonation and generation of radical which then undergoes rapid dimerization to disulfide species [32,38]. The second one, presumably dominating in higher pH, where deprotonation is an initial step, followed by its oxidation and radical formation [30,38]. Clearly the pH increase favors the anodic peak potential shift, which becomes almost pH independent in the basic solutions.…”

“…This feature is commonly used in biosensors for pesticide detection [26,27]. TC oxidation on bulk electrodes occurs at relatively high potentials, but the deposition of nanomaterials significantly reduces TC oxidation overpotential [11,[28][29][30][31]. Among other nanomaterials, electrophoretically deposited CNPs(À) [11], and CNTs films [30][31][32][33] (including LbL deposition) were applied for this purpose.…”