Amperometric Thick-Film Strip Electrodes for Monitoring Organophosphate Nerve Agents Based on Immobilized Organophosphorus Hydrolase

Abstract

An amperometric biosensor based on the immobilization of organophosphorus hydrolase (OPH) onto screen-printed carbon electrodes is shown useful for the rapid, sensitive, and low-cost detection of organophosphate (OP) nerve agents. The sensor relies upon the sensitive and rapid anodic detection of the enzymatically generated p-nitrophenol product at the OPH/Nafion layer immobilized onto the thick-film electrode in the presence of the OP substrate. The amperometric signals are linearly proportional to the concentration of the hydrolyzed paraoxon and methyl parathion substrates up to 40 and 5 μM, showing detection limits of 9 × 10(-)(8) and 7 × 10(-)(8) M, respectively. Such detection limits are substantially lower compared to the (2-5) × 10(-)(6) M values reported for OPH-based potentiometric and fiber-optic devices. The high sensitivity is coupled to a faster and simplified operation, and the sensor manifests a selective response compared to analogous enzyme inhibition biosensors. The applicability to river water sampling is illustrated. The attractive performance and greatly simplified operation holds great promise for on-site monitoring of OP pesticides.

Cross-linked enzyme crystals of organophosphate hydrolase for electrochemical detection of organophosphorus compounds

“…The electrode performed best at pH 8.0. This is a similar result to previous reports examining immobilized OPH in the range pH 7.0-pH 8.5 (Mulchandani et al 1999a;Chough et al 2002;Wang et al 2003;Deo et al 2005). Analytical characterization of CLEC-OPH biosensor An electrode modified with the OPH crystal was compared to one modified with the non-crystal form.…”

“…This was unlikely to be due to water hydrolysis since no gas bubbles were observed. It may be due to the direct electrochemical oxidation of paraoxon, which has been reported previously at approximately this potential (Mulchandani et al 1999a). On the basis of this result, the applied potential was set at 0.95 V for further work.…”

Modified Cholinesterase Technology in the Construction of Biosensors for Organophosphorus Nerve Agents and Pesticides Detection

“…So the organophosphorus compounds act for OPH as a substrate. These types of biosensors offer, same as the cholinesterase ones, using optical, fluorescent, potentiometric or amperometric converters (Karnati et al, 2007;Mulchandani, et al 1999aMulchandani, et al , 1999bRogers et al, 1999;Wang et al, 2003). Also a field version for in-situ monitoring has been developed Mulchandani et al, 2001).…”

The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

“…50 An amperometric biosensor was used by Mulchandani et al for the detection of several organophosphate nerve agents. 51 The amperometric biosensor consisted of a thick strip of carbon coated with an organophosphorus hydrolase (OPH)-infused nafion film. When exposed to a liquid nerve agent, the OPH hydrolyzes the nerve agent to p-nitrophenol, which is electrochemically active, and oxidized by the application of an anodic potential.…”