A new electrochemical sensor based on oxidized capsaicin/multi-walled carbon nanotubes/glassy carbon electrode for the quantification of dopamine, epinephrine, and xanthurenic, ascorbic and uric acids

Capsaicin (CAP) was used as a redox mediator and added tomulti-walled carbon nanotubes (MWCNT) modified glassy carbon electrode (GCE), to be used in the quantitation of xanthurenic (XA), ascorbic (AA) and uric (UA) acids, along with the neurotransmitters dopamine (DA) and epinephrine (EP), one at a time, using cyclic voltammetry and chronoamperometry, in buffered aqueous solutions, pH 7.0. The presence, after oxidation of CAP on MWCNT/GCE, of two reversible redox systems, which can be understood through the formation of a reversible surface-confined quinone systems, is important for the redox catalysis. The obtained analytical curves for XA, AA, DA, EP and UA showed linear ranges, between 10 and 95, 5-75, 5-115, 50-1150 and 5-70 mu mol L-1, respectively. The detection limits were 8.76, 1.95, 1.80, 7.20 and 1.56 mu mol L-1 for XA, AA, DA, EP and UA, respectively. This oxidized CAP-based platform is reported for the first time and is able to detect the analytes at a micromolar level.

Automated summary

Capsaicin was used as a redox mediator on multi-walled carbon nanotubes modified glassy carbon electrode for quantitation of xanthurenic, ascorbic, and uric acids, along with dopamine and epinephrine. The presence of reversible redox systems after oxidation of capsaicin is important for redox catalysis, with detection limits ranging from 1.56 to 8.76 µmol L-1. This oxidized CAP-based platform is capable of detecting analytes at a micromolar level efficiently.