Development of a generic microelectrode array biosensing system

A new type of electrochemical cell has been developed for use in biosensor applications. Utilising a random array of platinum microdiscs as the workin g electrode, it incorporates a Ag/AgCl reference electrode and platinum aux iliary electrode into the tip of a polished glassy Teflon probe. Immobilisa tion of the biochemical moiety onto the surface of the probe is achieved us ing a mixture of polyurethane (PU) and polyethylene oxide (PEO). Enclosing the tip of the probe within a dialysis membrane completes the electrochemic al cell. The hydrophilic nature of the PU-PEO mixture ensures the biochemic al moiety is trapped in a stable, hydrophilic environment. The result is an all in one generic electrochemical sensor that can be used in a wide range of biosensor applications in both batch or flow injection modes,The unique features of this system are demonstrated in this paper using the glucose - glucose oxidase (GOD) system. Parameters affecting sensor performance were investigated in both batch and flow injection modes. In terms of sensitivi ty, reproducibility, equilibration time and linear dynamic range, the perfo rmance of the microdisc based sensing system was superior to similar macroe lectrode versions. Practical detection limits (0.1 mu M) were four-five ord ers of magnitude better for this system compared with a conventional electr ode system. The advantages of using this system in flow injection mode, par ticularly in terms of increased linear range, were also addressed. The over all linear range of our system (0.1 mu M-60 mM) is three-four orders of mag nitude greater than the conventional electrode system. (C) 2000 Elsevier Sc ience B.V. All rights reserved.