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Electrochemical and Electrocatalytic Properties of Imidazole Analogues of the Redox Cofactor Pyrroloquinoline Quinone
Author(s) -
Lumibao Claudine Y.,
Tillekeratne L. M. Viranga,
Kirchhoff Jon R.,
Fouchard David M. D.,
Hudson Richard A.
Publication year - 2008
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200804315
Subject(s) - pyrroloquinoline quinone , chemistry , redox , cyclic voltammetry , quinone , moiety , electrochemistry , amperometry , inorganic chemistry , imidazole , electrocatalyst , cofactor , quinoline , cysteine , ascorbic acid , stereochemistry , organic chemistry , electrode , food science , enzyme
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‐1 H ‐imidazolo[5,4‐f]quinoline‐7,9‐dicarboxylic acid ( 1 ) and 4,5‐dihydro‐4,5‐dioxo‐2‐methyl‐1 H ‐imidazolo[5,4‐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.