Evaluation of glucose biosensors based on Prussian Blue and lyophilised, crystalline and cross-linked glucose oxidases (CLEC (R))

Glucose biosensors based on lyophilised, crystalline and cross-linked gluco se oxidase (GOx, CLEC(R)) and commercially available lyophilised GOx immobi lised on top of glassy carbon electrodes modified with electrodeposited Pru ssian Blue are critically compared. Two procedures were carried out for pre paring the biosensors: (1) deposition of one layer of adsorbed GOx dissolve d in an aqueous solution followed by deposition of two layers of low molecu lar weight Nafion(R) dissolved in 90% ethanol, and (2) deposition of two la yers of a mixture of GOx with Nafion dissolved in 90% ethanol. The performa nce of the biosensors was evaluated in terms of linear response range for h ydrogen peroxide and glucose, detection limit, and susceptibility to some c ommon interfering species (ascorbic acid, acetaminophen and uric acid). The operational stability of the biosensors was evaluated by applying a steady potential of -50 mV versus Ag/AgCl to the glucose biosensor and injecting standard solutions of hydrogen peroxide and glucose (50 muM and 1.0 mM, res pectively, in phosphate buffer) for at least 5 h in a flow-injection system . Scanning electron microscopy was used for visualisation of the Prussian B lue redox catalyst and in the presence of the different GOx preparations on the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.