Reagentless amperometric detection of L-lactate on an enzyme-modified conducting copolymer poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic acid-1,4-naphthoquinone)

We have constructed a reagentless lactate sensor using lactate oxidase (LOD) covalently attached to an electropolymerized copolymer film, poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic acid- 1,4-naphthoquinone), poly(JUG-co-JUGA). Around 10(-12) M cm(-2) Of covalently bound enzymes are immobilized on these films. In aerated medium, the amperometric response versus lactate concentration shows a sensitivity of 350 +/- 50 muA M-1 cm(-2) for an applied potential of +0.5 V versus Ag\AgCl on a film-coated Pt electrode. In deaerated medium, the quinone group, conjugated with the polymer backbone, acts as an immobilized mediator. An amperometric response is observed on film-coated glassy carbon (GC) electrode at a potential as low as -0.1 V versus Ag\AgCl, with a sensitivity of 110 +/- 40 muA M-1 cm(-2). (C) 2003 Elsevier B.V. All rights reserved.