A superoxide dismutase-modified electrode that detects superoxide ion

A superoxide dismutase (SOD)-modified electrode, in which SOD is oriented on the gold electrode via a self-assembled monolayer of cysteine so as to allow its direct electrode reaction, possesses a bi-directional electrocatalysis for both the oxidation of superoxide ion (O-2(-)) to O-2 and the reduction of O-2(-) to H2O2 and functions as a third generation O-2(-) biosensor.