Flow injection amperometric detection at enzyme-modified gold nanoelectrodes

Gold nanotubular electrode ensembles were prepared by using electroless deposition of the metal within the pores of polycarbonate particle track-etched membranes. Glucose oxidase (Gox), used as a model enzyme, has been immobilized onto preformed self-assembled monolayers (mercaptoethylamine or mercaptopropionic acid) on electroless gold via cross-linking with glutaraldehyde or covalent attachment by carbodiimidel coupling. Flow-injection analysis systems in flow-through or wall-jet configurations using these Gox-modified nanoelectrodes are described. The influence of different experimental parameters (i.e., applied potential, flow rate, interferents...) on the analytical response of the sensor to glucose has been evaluated. Under optimized conditions, very reproducible results (standard deviations < 4%, n = 38) were obtained, linear calibration was achieved in the 2 x 10(-4) M to 3 x 10(-2) M concentration range and the detection limit was 2 x 10-4 M. Moreover, no significant interferences from species like ascorbic and uric acids were observed at a potential of + 0.9 V.