Biosensors for the detection of organophosphate exposure by a new diethyl thiophosphate-specific aptamer

Abstract

Objective An aptamer speci cally binding to diethyl thiophosphate (DETP) was constructed and incorporated in an optical sensor and electrochemical impedance spectroscopy (EIS) to enable the speci c measurement of DETP as a metabolite and a biomarker of exposure to organophosphates.Results DETP-bound aptamer was selected from the library using capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX). A colorimetric method revealed the aptamer had the highest a nity to DETP with a mean Kd value (± SD) of 0.103 ± 0.014 µM. Changes in resistance using EIS showed selectivity of the aptamer for DETP higher than for dithiophosphate (DEDTP) and diethyl phosphate (DEP) which have similar structure and are metabolites of some of the same organophosphates. The mean (± SD) of percentage of altered resistance of DETP was calculated at 47.5 ± 8.8% which was signi cantly higher than of DEDTP at 14.3 ± 1.5% and of DEP at 7.0 ± 1.4%.Conclusions The current method showed a great promise in using the DETP-speci c aptamer to detect the exposure history to organophosphates, by measuring their metabolite, although degradation of organophosphate parent compounds might occur.

A nonenzymatic reduced graphene oxide-based nanosensor for parathion

“…Most of the electrochemical nanobiosensors for the detection of OPs (e.g., methyl parathion, ethyl parathion, fenitrothion, chlorpyrifos, paraoxon, ethion, and acephate) are based on the inhibition of acetylcholinesterase (AChE) activity (an indirect method) [8][9][10]. Some organic molecules and metal cations also act as an inhibitor of AChE.…”