Disposable potentiometric sensors for monitoring cholinesterase activity

A highly sensitive disposable screen-printed butyrylcholine (BuCh) potentiometric sensor, based on heptakis (2,3,6-tri-o-methyl)-β-cyclodextrin (β-CD) as ionophore, was developed for butyrylcholinesterase (BuChE) activity monitoring. The proposed sensors have been characterized and optimized according to the constituents of homemade printing carbon ink including β-CD, anionic sites, and plasticizer. The fabricated sensor showed Nernstian responses from 10−6 to 10−2 mol L−1 with detection limit of 8 × 10−7 mol L−1, fast response time (1.6 s) and adequate shelf-life (6 months). Improved selectivity towards BuCh with minimal interference from choline (Ch) was achieved and the sensor was used for determination of 0.06–1.25 U mL−1 BuChE. The developed disposable sensors have been successfully applied for real-time intoxication monitoring through assaying cholinesterases (ChEs) activity in human serum. Determination of organophosphate pesticide was conducted by measuring their inhibition of BuChE with successful assaying of malathion in insecticide samples with high accuracy and precision.