Electrochemical and Electrocatalytic Properties of Imidazole Analogues of the Redox Cofactor Pyrroloquinoline Quinone |
| |
Authors: | Claudine Y Lumibao L M Viranga Tillekeratne Jon R Kirchhoff David M D Fouchard Richard A Hudson |
| |
Institution: | 1. Department of Chemistry, College of Arts & Sciences, University of Toledo, Toledo, OH, 43606, USA;2. Department of Medicinal & Biological Chemistry, College of Pharmacy, University of Toledo, Toledo, OH, 43606, USA |
| |
Abstract: | The electrochemical and electrocatalytic properties of two synthetic imidazole analogues of the redox cofactor pyrroloquinoline quinone (PQQ) were evaluated. Cyclic voltammetry measurements as a function of pH indicated that both 4,5‐dihydro‐4,5‐dioxo‐1H‐imidazolo5,4‐f]quinoline‐7,9‐dicarboxylic acid ( 1 ) and 4,5‐dihydro‐4,5‐dioxo‐2‐methyl‐1H‐imidazolo5,4‐f]quinoline‐7,9‐dicarboxylic acid ( 2 ) undergo a reversible reduction of the o‐quinone moiety below pH 8 with potentials slightly more positive than those observed for PQQ. Upon incorporation into a polypyrrole membrane on the tip of a glassy carbon electrode, 1 and 2 exhibited electrocatalytic properties sufficient for the indirect amperometric detection of cysteine. The response for cysteine was linear up to 1 mM over a wide pH range. Detection limits (S/N=3) were in the μM range and dependent on the solution pH. Interference from redox active species such as dopamine and uric acid were minimized by the pH‐dependent redox potentials of 1 and 2 and thus the ability to tune the detection potential. |
| |
Keywords: | o‐Quinone electrocatalysts Pyrroloquinoline quinone Thiol detection Electrochemical sensor |
|
|