Organophosphorus hydrolase multilayer modified microcantilevers for organophosphorus detection

We report a biosensor based on organophosphorus hydrolase (OPH) multilayer modified microcantilever (MCL) for detection of organophosphorus compounds (OPs). The assay is based on substrate-dependent bending of the CPH functionalized MCLs. The cantilever bending amplitude at equilibrium was a function of the concentration of paraoxon with the dynamic range extending from 10(-7) to 10(-3) M. The lower detection limit of approximately 10(-7) M for paraoxon was an order of magnitude better than the OPH-based potentiometric and optical biosensors based on pH modulation. There was a good intra-sensor and an acceptable inter-sensor reproducibility as evidenced by the standard errors of 5% and 15%, respectively. OPs measured using this technique included parathion and diisopropyl. fluorophosphate (DFP) in the order of paraoxon > DFP > parathion. The conformational change of the OPH was most likely the main origin of MCL bending. (c) 2006 Elsevier B.V. All rights reserved.