Polypyrrole-based potentiometric phosphate biosensor

A phosphate biosensor based on potentiometric detection mode is described. Purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD) were immobilised into polypyrrole films for potentiometric measurement of phosphate in 0.05 M barbitone buffer (pH 7.8) which contain 10 mM inosine. A minimum detectable amount Of 1.0 mu M phosphate and a linear concentration range of 5-25 mu M were achieved enabling sensitive potentiometric detection and a wide linear concentration range, The presence of uric and ascorbic acids had the least effect on the performance of the PPy-PNP-XOD-Fe(CN)(6)(4-) biosensor and therefore will not have any effect on phosphate measurement at levels normally present in water. (C) 2009 Elsevier B.V. All rights reserved.