Immobilization of monoamine oxidase on eggshell membrane and its application in designing an amperometric biosensor for dopamine

An amperometric biosensor for dopamine is described. It is based on the enzyme monoamine oxidase immobilized on a glutaraldehyde-activated eggshell membrane that was deposited on a glassy carbon electrode. The Michaelis-Menten constant (Km) is 0.087 mM. Optimum pH and temperature conditions were obtained at pH 7.0 and 37 A degrees C, respectively. The sensor showed a detection limit of 20 mu M, a linear range from 50 mu M to 250 mu M, and a storage stability of similar to 25 days. In order to further improve the performance, a Nafion coating was applied on the electrode surface which gave favorable results with respect to shelf life of the enzyme (similar to 40 days), the limit of detection, and the selectivity over ascorbic acid and uric acid.