Potentiometric biosensors featuring immobilized choline esterase and a pH-responsive film electrode

Potentiometric biosensors based on choline esterase, immobilized in fluoroplastic and cellulose acetate matrices directly at the surface of a pH-responsive film electrode, are examined. Characteristics of the sensors are compared in solutions of a substrate (acetylcholine iodide). The influence of some divalent cations on the catalytic activity of both the native and immobilized enzyme is studied. The choline esterase activity is found to essentially depend on its state (native or immobilized), the matrix nature, and membrane composition. The sensors proposed feature a wide operation range in substrate solutions, fast response time, and long lifetime.