Biosensor for organophosphorus nerve agent

Organophosphorus (OP) compounds, among the most toxic substances, are widely used as pesticides, insecticides and chemical warfare agents. Because of their neurotoxic effects on humans, and on infants in particular, and their increasing occurrence in the environment and water, their use has become a hotly debated issue. Consequently, there is a growing interest in their rapid, sensitive, selective, and reliable detection and determinations for the protection of our food and water supply and the environment.; In this dissertation, first, two highly sensitive biosensors for PNP were developed using p-nitrophenol degrader Arthrobacter sp. JS443 as the prerequisite for developing a highly sensitive biosensor to monitor OP pesticides. Then, we reported the constructions of biosensors for highly selective, sensitive and rapid quantitative determination of organophosphate pesticides with p-nitrophenol substituent using either Arthrobacter sp. JS 443 and purified OPH or p-nitrophenol degrader Pseudomonas putida JS444 with surface-expressed organophosphorus hydrolase (OPH). OPH catalyzed the hydrolysis of organophosphorus pesticides with p-nitrophenol substituent such as paraoxon, methyl parathion, parathion, fenitrothion and EPN to release p-nitrophenol or 3-methyl-4-nitrophenol that was oxidized by the enzymatic machinery of Arthrobacter sp. JS 443 or Pseudomonas putida JS444 to carbon dioxide through electrochemically active intermediates while consuming oxygen and releasing nitrite. The oxygen consumption or oxidization current of the intermediates was measured and correlated to the concentration of organophosphates.