Luminol electrochemiluminescence with screen-printed electrodes for low-cost disposable oxidase-based optical sensors

This paper reports the use of screen-printed electrodes polarised at a fixed potential to trigger luminol electrochemiluminescence in a batch system. Choline oxidase is used as a model H2O2-generating oxidase. The enzyme is immobilised by ionic interactions in DEAE-Sepharose beads before entrapment in a poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) photocrosslinked polymer. The light signal is transmitted to a photomultiplier tube via a fibre optic facing the electrode. Under optimised conditions, at 450 mV vs. Ag/AgCl, in 30 mM veronal-HCl buffer, pH 9, containing 50 mu M luminol, the linear range extends from 2 x 10(-8) to 1 x 10(-4) M choline.