Glutamate sol-gel amperometric biosensor based on co-immobilised NADP+ and glutamate dehydrogenase

In this work the preparation and electrochemical characterisation of a new glutamate amperometric sol-gel biosensor is described. A carbon paste electrode was electrochemically modified with the phenothiazine dye methylene green ( MG ). The NADP + and glutamate dehydrogenase were co-immobilised in a sol-gel matrix. When coupled to a flow injection system ( FIA ) the biosensor showed good electrocatalytic activity towards NADPH oxidation at the potential of + 0.3 V vs. Ag/AgCl; KCl sat., which represents a strong overpotential reduction. The biosensor yielded a linear response from 5.0 × 10 −5 to 1.0 × 10 −2 M glutamate concentration, with a detection limit of 5 × 10 −6 M and reproducibility of results better than 2.3% ( RSD ). Moreover, the implemented biosensor showed to be still useful after 7 months, 500 determinations.