Novel type cholinesterase sensor based on SPV measurement technique

The surface photovoltage (SPV) technique was applied to the fabrication of a novel type biosensor based on immobilized cholinesterase. Two types of cholinesterase were utilized, acetylcholinesterase and butyrylcholinesterase, depending on the types of substrates. On the surface of the silicon wafer the cholinesterase layers were immobilized by using 3-aminopropyltriethoxysilane and glutaraldehyde. Characteristics of the sensor were studied in phosphate-buffered saline containing 15 mM NaCl and 1 mM phosphate buffer, pH 7.0. The detection limits of the substrates were 9.0×10−7 M, 2.7×10−6 M, and 4.1×10−6 M for butyrylthiocholine iodide, acetylcholine iodide, and acetylcholine chloride, respectively. The activity of the cholinesterase was inhibited by the presence of alkaloids such as physostigmine and neostigmine.