A superoxide anion electrochemical sensor based on the direct electrochemistry of superoxide dismutase assembled layer-by-layer at the L-cysteine modified gold electrode

摘要

Asuperoxide anion (O2?–) biosensor has been developed basedon layer-by-layer assembled poly-(diallyldimethylammonium) (PDDA) and superoxide dismutase (SOD) on theL-cysteine (Cys) modified gold (Au) electrode. In 25 mMphosphate buffer solution (pH 7.2),the {SOD/PDDA}n/Cys/Au electrode shows a pair of well-defined and nearlyreversible peak at ~ 84 mV vs SCE, confirming the direct electrochemistry ofSOD. Based on the bifunctional enzymatic catalytic activities of SOD to theoxidation and reduction of O2?–, the developed {SOD/PDDA}5/Cys/Au electrode exhibits good analytical characteristics in thedetection of O2?–, such as low detection limit,good stability, reproducibility, selectivityand particularly a wide linear range (0.5 ~546 mM).