Screen-printed electrodes as disposable or reusable optical devices for luminol electrochemiluminescence

Screen-printed electrodes are used to trigger luminol electrochemiluminescence at 450 mV versus printed Ag/AgCl. Choline oxidase (ChOD) is immobilized on the working electrode surface by ionic interactions with a diethylaminoethyl (DEAE) modified polymer (Sepharose or dextran) before entrapment in a poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) photocrosslinked matrix. A fiber optic faces the electrode and is connected to the photomultiplier tube of a luminometer. The effect of the working conditions is studied, in terms of buffer nature and pH. DEAE-Sepharose-based screen-printed electrodes can be used either as disposable devices in 0.2 M carbonate buffer pH 9.5 or as reusable devices (ca. 25 assays) in 30 mM veronal-HCl buffer pH 9.5. The use of DEAE-dextran instead of DEAE-Sepharose allows to easily control the amount of deposited ionic polymer, but the operational stability of the sensors is decreased (ca. seven assays). (C) 2001 Elsevier Science B.V. All rights reserved.