Screen-printed electrode microarray for electrochemiluminescent measurements

A microarray of nine screen-printed (SP) graphite electrodes was used to develop multi-parametric electrochemiluminescent (ECL) biochip. The whole biochip is based on the ECL detection of enzymatically generated H2O2. The intrinsic performances of this electrode array were evaluated through the cyclic-voltammetric experiments in 0.1 M ferricyanide. The variations of the specific behaviours (oxidation potential and current) of such a redox mediator were then used to reach the reproducibility of the SP arrays, i.e. 2% for electrode-to-electrode and 4% for biochip-to-biochip variations. In a similar way, electrochemiluminescent cyclic-voltammetric experiments were performed to characterize the ECL reaction triggered at the surface of a SP carbon electrode array. An optimum luminol oxidation potential of +650 mV versus platinum pseudo-reference was found with a reproducibility of 4.4%. The different sensing layers were obtained through the entrapment of glucose oxidase and lactate oxidase in PVA-SbQ (poly(vinyl alcohol) bearing styrylpyridinium groups) photopolymer deposited at the surface of two from the nine electrode array. An automatic nano-spotter was employed to precisely drop spots of entrapped enzyme at an electrode surface. Therefore, ECL measurements were performed to establish calibration curves by using a charged coupled device (CCD) camera. Linear ranges, detection limits and reproducibility of these biochips were investigated as a demonstrative example of oxidase-based ECL detection/biosensor. In the present paper, the achieved biosensor arrays allowed the simultaneous detection and quantification Of L-lactate and D-glucose with detection limits of 3 and 10 mu M, respectively. (c) 2005 Elsevier B.V. All rights reserved.