Ultrasensitive detection of organophosphate insecticides by carbon nanotube field-effect transistor

Abstract

Carbon nanotube sensors were capable of detecting organophosphate insecticide binding to recombinant acetylcholinesterase (rAChE) immobilized on the sensor. The carbon nanotube sensors were fabricated by chemical vapor deposition method and it showed field effect transistor property. rAChE was immobilized by specific binding of NTA-Ni and His tag on the reverse side of the carbon nanotube sensor. The current between the source and drain was measured after incubation of various concentrations of organophosphates with immobilized rAChE. I-V gate curves were obtained by plotting the current as a function of the potential applied to the back gate. The I-V gate curves showed a positive shift in a dose dependent manner, while no shifts were observed when an herbicide was added to the sensor and organophosphates were withdrawn on recombinant calmodulin immobilized surface. In spite of different inhibition effects, two organophosphates showed similar dose response curves in measuring I-V gate correlation with the rAChE-immobilized CNT sensors, suggesting that the binding of organophosphates to rAChE may be sequestered from the inhibition activity of those to the enzyme.

History and New Developments of Assays for Cholinesterase Activity and Inhibition

“…Recombinant AChE was immobilized on the reverse side of the carbon nanotube sensor for detecting OP insecticides. 95 The current between the source and the drain was measured after incubation of various concentrations of OPs with immobilized AChE. Two OPs showed similar dose-response curves in measuring I ds -V gate correlation with the AChEimmobilized CNT sensors.…”

“…The subsequent functionalization of CNT with bioreceptors leads to the development of various novel biosensors. Recombinant AChE was immobilized on the reverse side of the carbon nanotube sensor for detecting OP insecticides . The current between the source and the drain was measured after incubation of various concentrations of OPs with immobilized AChE.…”