酵素固定化ポリイオン複合膜を用いるアセチルコリンセンサーの作製

抄録

An acetylcholine esterase (AcE)-attached polyion complex membrane containing choline oxidase (ChOD) was prepared, and was used for detecting acetylcholine. The preparation method proceeded for 2 steps. First, a polyion complex membrane containing ChOD was prepared on a glassy carbon electrode by dropping poly-L-lysine, polystylene sulfonate and ChOD solutions onto the surface. After drying, AcE was bound to the surface of the membrane using glutaraldehyde. The membrane was used to detect acetylcholine; +1 V vs. Ag/AgCl was applied to the electrode to detect produced-hydrogen peroxide. Immediately after the addition of acetylcholine, the oxidative current was increased, and reached a steady state within 15 s. The response current was proportional to the acetylcholine concentration up to 0.2 mM, and the lower detection limit was 5 μM. The interfering current from L-ascorbate was rather small: the current-response ratio from the same concentrations of L-ascorbate and acetylcholine was 60%, because of the restricted penetration of L-ascorbate through the membrane. The long-term stability of the electrode was examined; after 40 days the magnitude of the current response became half of the initial value. Nevertheless, because the form of the calibration curve did not change, the electrode could be used for detecting acetylcholine. Based on these results, the AcE-attached polyion complex membrane containing ChOD can be used for an acetylcholine biosensor.