Organophosphates, amongst the most toxic substances known, are used widely as pesticides, insecticides and chemical warfare agents. These compounds are potent acetylcholinesterase (AChE) inhibitors. Since AChE is present in all vertebrates, the potential damage caused by OPs to non-target organisms, including humans, is extremely high. Therefore, there is an urgent need for selective, sensitive and rapid analytical devices to monitor these compounds in the field.

This presentation will review our research on biosensors based on organophosphorus hydrolase (OPH), an enzyme that catalyzes the hydrolysis of organophosphorus nerve agents including nerve gases and pesticides, and genetically engineered cells expressing the OPH on its cell surface. These biological recognition elements were integrated with potentiometric, amperometric, optical and conductometric transducers to build field-deployable enzyme- and microbial-biosensors for sensitive, selective, rapid and direct determination of organophosphate pesticides and nerve gases. The enzyme was also used for on-chip precolumn hydrolysis followed by electrophoretic separation and contactless conductivity detection of hydrolysis products to screen and fingerprint the organophosphates.