A novel amperometric biosensor based on a co-crosslinked L-lysine-α-oxidase/overoxidized polypyrrole bilayer for the highly selective determination of L-lysine.

Antonio Guerrieri, Rosanna Ciriello, Tommaso R I Cataldi

Index: Anal. Chim. Acta 795 , 52-9, (2013)

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Abstract

An amperometric biosensor for the determination of L-lysine based on L-lysine-α-oxidase immobilized by co-crosslinking on a platinum electrode previously modified by an overoxidized polypyrrole film is described. The optimization of experimental parameters, such as pH and flow rate, permitted to minimize significantly substrate interferences even using a low specific, commercial enzyme. The relevant biases introduced in the measurement of lysine were just about 1% for L-arginine, L-histidine and L-ornithine, roughly 4% for L-phenylalanine and L-tyrosine. The developed approach allowed linear lysine responses from 0.02 mM up to 2 mM with a sensitivity of 41 nA/(mM × mm(2)) and a detection limit of 4 μM (S/N=3). No appreciable loss in lysine sensitivity was observed up to about 40 days. Allowing polypyrrole layer to remove interference from electroactive compounds, the present method revealed suitable to detect L-lysine in a pharmaceutical and cheese sample, showing a good agreement with the expected values.Copyright © 2013 Elsevier B.V. All rights reserved.