Amperometric biosensor based on a functionalized gold electrode for the detection of antioxidants

Electrocatalytic evaluation of DNA damage by superoxide radical for antioxidant capacity assessment

“…Two reports described the use of AA as a standard antioxidant against superoxide radical, but the biolayer on the electrode was formed by cytochrome c or SOD [2]; or the electrochemically generated radical was detected directly on a glassy carbon disk electrode [14]. From our previous work on antioxidant activity against OH Å on DNA-CPE, it can be concluded that AA seemed to be less efficient as a scavenger of superoxide radical than hydroxyl radicals.…”

“…Therefore, overproduction of ROS can be dangerous for cells [2]. The superoxide anion radical (O ÅÀ 2 ) is the primary component of ROS and the most abundant radical in biological systems, resulting from the single-electron reduction of oxygen [3].…”

“…Electrochemical biosensors use two main sources of ROS: OH Å and O ÅÀ 2 . The former can be generated photocatalytically [7] or by Fenton reaction in DNA-based antioxidant sensors [8,9], and the latter is mostly enzymatically [2,10,11] but also chemically [3,12,13] or electrochemically [14] formed for the determination of both superoxide radical and AOC. Sensors based on O ÅÀ 2 commonly rely on the immobilization of cytochrome c, which is reduced by superoxide radical, on gold [2][3][4], carbon [15] or screen printedAu-electrode [16] surfaces, where it is reoxidized.…”

“…The former can be generated photocatalytically [7] or by Fenton reaction in DNA-based antioxidant sensors [8,9], and the latter is mostly enzymatically [2,10,11] but also chemically [3,12,13] or electrochemically [14] formed for the determination of both superoxide radical and AOC. Sensors based on O ÅÀ 2 commonly rely on the immobilization of cytochrome c, which is reduced by superoxide radical, on gold [2][3][4], carbon [15] or screen printedAu-electrode [16] surfaces, where it is reoxidized. To enhance the electrical contact between cytochrome c and the electrode and to increase the surface coverage of this compound, several immobilization strategies have been proposed mostly based on SAMs of thiols of different length [2][3][4]15] and hemin modified electrodes [17].…”

“…Sensors based on O ÅÀ 2 commonly rely on the immobilization of cytochrome c, which is reduced by superoxide radical, on gold [2][3][4], carbon [15] or screen printedAu-electrode [16] surfaces, where it is reoxidized. To enhance the electrical contact between cytochrome c and the electrode and to increase the surface coverage of this compound, several immobilization strategies have been proposed mostly based on SAMs of thiols of different length [2][3][4]15] and hemin modified electrodes [17]. However, these sensors present the interference of H 2 O 2 , uric acid and also some electrical communication problems between the protein and the electrode.…”