Impedance sensor based on N-acetyl-L-cysteine for evaluation of antioxidant activity against hydroxyl radicals

Hydroxyl radical is the most aggressive and dangerous product of incomplete reduction of oxygen in the body, therefore its determination and the influence of various antioxidants on the inhibition of OH-radicals is an urgent task. An impedance-metric sensor for the determination of hydroxyl radicals based on a graphite electrode modified with electrochemically deposited gold and self-organizing monolayer of N-acetyl-L-cysteine (ACC) has been proposed. The use of ACC causes high selectivity of the sensor, and the use of non-Faraday impedance as a method of analytical signal registration allows to reach the detection limit of OH-radicals of 0.01 nM with a linear range of detectable concentrations of 0.08-8 nM. The developed sensor has been successfully applied to evaluate the activity of some antioxidants (ascorbic acid, glutathione, coenzyme Q10) in relation to OH-radicals.