Choline biosensor constructed with chitinous membrane from soldier crab and its application in measuring cholinesterase inhibitory activities

An amperometric flow-injection choline biosensor was assembled utilizing natural chitinous membrane as the supporting material for biocatalyst immobilization, and the membrane was purified from Taiwanese soldier crab, Mictyris brevidactylus. The chitinous membrane (<50.0 μm in thickness) was covalently immobilized with choline oxidase (EC 3.1.1.17 from Alcaligenes sp.) and then attached onto the platinum electrode of an amperometric flow cell. The flow cell served as the choline sensing device of the proposed FIA system. The sensor signal (peak height of the FIAgram) was linearly related to choline concentration (r = 0.999 for choline up to 5.0 mM) with low detection limit (S/N > 3 for 10.0 μM choline) and high reproducibility (CV < 3% for 1.0 mM choline, n = 7). The system was proved to be useful in measuring cholinesterase inhibitory activities of synthetic chemicals or natural products.