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Assay of serum cholinesterase activity by an amperometric biosensor based on a co-crosslinked choline oxidase/overoxidized polypyrrole bilayer

Abstract

Based on choline oxidase immobilized by co-crosslinking on a overoxidised polypyrrole modified platinum electrode, a novel electrochemical assay for cholinesterase activity in human serum has been developed. The assay was performed by adding an aliquot of cholinesterase standard solution or serum sample to a phosphate buffer containing a choline or thiocholine ester and measuring the oxidation current of hydrogen peroxide at the rotating modified electrode polarized at +0.7 V vs SCE. The influence of some experimental parameters like pH of the assay, mass transport at the electrode, type and concentration of cholinesterase substrate has been studied and optimised. A reversible inhibition on choline oxidase from cholinesterase substrates has been evidenced for the first time, increasing in the order acetylcholine, butyrylcholine and s-butyrylthiocholine. Wide linear range, fast response time and appreciable long term stability were assured for both acethyl- and butyrylcholinesterase assays. Allowing polypyrrole layer to efficiently remove interference from electroactive compounds in sample, the present method revealed suitable to detect butyrylcholinesterase in human serum at activities down to 0.5 U L-1. The validation with a reference spectrophotometric method showed no significative differences when human serum samples were analysed.

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Supplementary files

Publication details

The article was received on 24 Oct 2017, accepted on 06 Jan 2018 and first published on 08 Jan 2018


Article type: Paper
DOI: 10.1039/C7AN01757J
Citation: Analyst, 2018, Accepted Manuscript
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    Assay of serum cholinesterase activity by an amperometric biosensor based on a co-crosslinked choline oxidase/overoxidized polypyrrole bilayer

    R. Ciriello , S. Lo Magro and A. Guerrieri, Analyst, 2018, Accepted Manuscript , DOI: 10.1039/C7AN01757J

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