A novel impedimetric sensor based on N-acetyl-L-cysteine for the determination of hydroxyl radicals in cell cultures in vitro.

We report a novel impedimetric sensor based on a graphite electrode impregnated with polyethylene and paraffin under vacuum (IGE) modified with electrochemically deposited gold and a self-assembled monolayer of N-acetyl-L-cysteine (NAC/Au/IGE) for selective and sensitive determination of extracellular hydroxyl radicals (OH•) generated by living cells. The application of a sulphur-containing molecule oxidized by OH• predicts the high selectivity of the sensor, and the utilization of the non-faradaic impedance spectroscopy for recording an analytical response makes it possible to achieve superior sensitivity with a detection limit of 0.01 nM and a linear dynamic range of 0.08-8 nM. Meanwhile, NAC/Au/IGE demonstrated a strong potential of detecting OH• generated by biological objects via successful determination of extracellular hydroxyl radicals generated by normal fibroblast cells and prostate carcinoma cells.