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

Abstract

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 μM luminol, the linear range extends from 2 × 10⁻⁸ to 1 × 10⁻⁴ M choline.