In Situ Electro-organic Synthesis and Functionalization of Catechol Derivative on Carbon Black and Its Interference-free Voltammetric pH Sensor Application ^∗

Abstract

We report an easy electrochemical route for preparing a catechol derivative (di-ferulyl sesamol derivative, designated as CA-Fer) functionalized low-cost carbon black (CB) modified electrode in a neutral pH buffer solution. As synthesized precursor organic compound, CA-Fer has been electrochemically oxidized over the CB by potential cycling treatment in pH 7 PBS that leads to a high redox active CA-Fer-catechol derivative (CB@CA-Fer-Redox), which exhibited a well-defined and stable surface-confined redox response at Eo’ = 0.150 V vs Ag/AgCl with a surface excess value = 50.46 nmol cm−2. Unlike the conventional redox active mediators, GCE/CB@CA-Fer-Redox modified electrode has failed to show any mediated oxidation/reduction response to various electro-active biochemicals and chemicals, viz., ascorbic acid, glucose, cysteine, caffeic acid, hydrazine, hydrogen peroxide, uric acid, dopamine, creatinine, urea, nitrite, sulfide and sulfate ions, depicting a clear advantage of using it as a voltammetric pH sensor for real-time applications. The modified electrode showed a linear voltammetric potential signal against pH in a window, 3-11, with a slope value of (∂Ep/∂pH) = -59±3 mV pH-1. As an independent study, a CA-Fer-Redox modified three-in-one screen printed electrode was developed, and a sensitive voltammetric pH analysis of some chemical biochemical real sample systems were demonstrated.

Moving towards in pouch diagnostics for ostomy patients: exploiting the versatility of laser induced graphene sensors

“…Similar non Nernstian gradients were found with the LIG-Riboflavin system when switching between 2-electrode and 3-electrode configurations. It is noteworthy that Srinivas et al (2022) also observed a similar non Nernstian (2H + /3e − ) behaviour (45 mV) with a carbazole-quinone derivative and attributed the response to the orientation/interaction of the redox probe on the surface [ 70 ]. The change in behaviour upon being surface confined is supported by the work by Lee et al (2013) where the pKa and hence protonation of the redox species can be modified by the surface interactions [ 73 ].…”