Abstract

LOURENCO, R.J.M.; SERRALHEIRO, M.L.M.  and  REBELO, M.J.F.. Development of a New Amperometric Biosensor for Lactose Determination. Port. Electrochim. Acta [online]. 2003, vol.21, n.2, pp.171-177. ISSN 0872-1904.

A new amperometric biosensor for lactose determinaion in raw milk was developed through the simultaneous immobilization of β-galactosidase and galactose oxidase on a derivatised polyethersulphone membrane. β-galactosidase catalyses the hydrolysis of lactose into galactose and glucose and galactose oxidase catalyses the oxidation of galactose into galactonic acid and H₂O₂. The membranes with the two immobilized enzymes were then used in an amperometric sensor, by oxidation of the H₂O₂ formed, at a Pt electrode of an Universal Sensors electrode base system. The sensitivity and the reproducibility of the biosensor thus formed were found to be 6.81 and 0.72 nA.M^-1, respectively. Biosensors were found to be stable for 20 days.

Keywords : biosensor; lactose; amperometric; stabilization; b-galactosidase; galactose oxidase.

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