Electrodeposited glucose oxidase/anionic clay for glucose biosensors design

Abstract

An amperometric glucose biosensor was developed using an anionic clay matrix (layered double hydroxide (LDH), Ni/Al–NO 3) for the immobilization of glucose oxidase (GOx). The biofilm was prepared by electrodeposition of the clay and GOx and subsequent cross-linking with glutaraldeyde. The Pt surface modified with the Ni/Al–NO 3 shows a much reduced noise, giving rise to a better signal to noise ratio for the currents relative to H 2O 2 oxidation, and a linear range for H 2O 2 determination wider than the one observed for bare Pt electrodes. Under the optimised operative conditions, the performances of the biosensor have been evaluated by measuring the steady-state currents (at +0.45 V versus SCE) to increasing concentrations of glucose in “air saturated” 0.1 M phosphate buffer (pH 7.0). Both batch and flow injection modes were explored. The response to glucose was linear up to 8.0 and 12.0 mM, and the sensitivities were 7.7 ± 0.1 and 19.1 ± 0.2 mA M −1 cm −2, respectively. The current response of the biosensors does not significantly change for 15 consecutive days in batch and for 10 days in flow, at least, if stored at 4 °C in phosphate buffer, when not in use. The effects of interferants and applicability to fruit juices and soft drinks analysis of the biosensor were also investigated.