Abstract:
|
This work presents a comparative study between two different methods for the preparation of mediator-modified screen-printed electrodes,
to be used as detectors in a reliable flow injection system for the determination of the nicotinamide adenine dinucleotide (NADH) coenzyme.
The best strategy was selected for the final development of compact biosensors based on dehydrogenase enzymes. For the first immobilisation
strategy, different redox mediators were electropolymerised onto the SPE surface. The second immobilisation strategy was carried out using
polysulfone–graphite composites, which were deposited by screen-printing technology onto the screen-printed electrode (SPE) surface. Both
methods achieved an effective and reliable incorporation of redox mediators to the SPE configuration. Finally, a flow system for ammonium
determination was developed using a glutamate dehydrogenase (GlDH)-Meldola’s Blue (MB)-polysulfone-composite film-based biosensor.
The stability of the redox mediators inside the composite films as well as the negligible fouling effect observed on the electrode surface improve the
repeatability and reproducibility of the sensors, important features for continuous analysis in flow systems. Furthermore, the optimised bio/sensors,
incorporated in a flow injection system, showed good sensitivities and short response times. Such a good analytical performance together with
the simple and fast sensor construction are interesting characteristics to consider the polysulfone-composite films as attractive electrochemical
transducer materials for the development of new dehydrogenase-based SPEs. |