Thick-film electrodes for measurement of superoxide and hydrogen peroxide based on direct protein?electrode contacts

Abstract

Cytochrome c was immobilized on screen-printed thick-film gold electrodes by a self-assembly approach using mixed monolayers of mercaptoundecanoic acid and mercaptoundecanol. Cyclic voltammetry revealed quasi-reversible electrochemical behavior of the covalently fixed protein with a formal potential of +10 mV vs. Ag/AgCl. Polarized at +150 mV vs. Ag/AgCl the electrode was found to be sensitive to superoxide radicals in the range 300-1200 nmol L(-1). Compared with metal needle electrodes sensitivity and reproducibility could be improved and combined with the easiness of preparation. This allows the fabrication of disposable sensors for nanomolar superoxide concentrations. By changing the electrode potential the sensor can be switched from response to superoxide radicals to hydrogen peroxide-another reactive oxygen species. H(2)O(2) sensitivity can be provided in the range 10-1000 micromol L(-1) which makes the electrode suitable for oxidative stress studies.

Electrochemical properties of cytochroms P450 using nanostructured electrodes: Direct electron transfer and electro catalysis

“…This means that cytochrome c is only an electron transfer protein, while P450 in reduced form can bind oxygen [2,3]. Besides, cytochrome c may be used in such a bienzyme system as antioxidant and counter agent for hydrogen peroxide or superoxide anion radicals [50]. Catalytic behaviour of the DDAB/Au/P450 2B4 electrodes was studied by CV, SWV, and amperometry.…”

Indirect Electrochemical Sensing of Radicals and Radical Scavengers in Biological Matrices

“…A number of highly sensitive electrochemical biosensors for detection of free oxygen radicals and antioxidants have been reported. [7][8][9][10][11] They are based on the use of immobilized redox proteins, especially cytochrome C, which is easily reduced by the oxygen radicals, and typical catalytic currents can be measured. All these protein-based biosensors suffer from a limited stability, and their preparation is rather time consuming.…”

Electrochemical and Sensorial Behavior of SOD Mutants Immobilized on Gold Electrodes in Aqueous/Organic Solvent Mixtures

“…Thus, SOD electrodes have the inherent advantage of a higher sensitivity. In addition, SOD does not show a pseudoperoxidase activity as reported for cyt.c [12,21], which may falsify the biosensors signal if not carefully controlled. SOD is very selective for superoxide providing the basis for a very specific sensor.…”