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Biosensors 2018, 8(1), 16;

Ultrasensitive Determination of Malathion Using Acetylcholinesterase Immobilized on Chitosan-Functionalized Magnetic Iron Nanoparticles

Department of Analytical Chemistry, São Paulo State University (UNESP), 14800-900 Araraquara, SP, Brazil
Department of Natural Sciences, Federal University of Maranhão (UFMA), 65200-000 Pinheiro, MA, Brazil
Department of Chemistry, Federal University of Maranhão (UFMA), 65080-805 São Luís, MA, Brazil
UNESP, National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), UNESP, P.O. Box 355, 14800-900 Araraquara, SP, Brazil
Author to whom correspondence should be addressed.
Received: 9 January 2018 / Revised: 7 February 2018 / Accepted: 7 February 2018 / Published: 13 February 2018
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A renewable, disposable, low cost, and sensitive sensor for the detection of organophosphorus pesticides was constructed by immobilizing the acetylcholinesterase enzyme (AChE), via glutaraldehyde, on magnetic iron nanoparticles (Fe3O4) previously synthesized and functionalized with chitosan (CS). The sensor was denoted AChE/CS/Fe3O4. The magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. Acetylthiocholine (ATCh) was incubated with AChE/CS/Fe3O4 and attached to a screen-printed electrode using a magnet. The oxidation of thiocholine (from ATCh hydrolysis) was monitored at an applied potential of +0.5 V vs. Ag/AgCl(KClsat) in 0.1 mol L−1 phosphate buffer solution (pH 7.5) as the supporting electrolyte. A mixture of the pesticide malathion and ATCh was investigated using the same procedure, and the results were compared and expressed as inhibition percentages. For determination of malathion, the proposed sensor presented a linear response in the range from 0.5 to 20 nmol L−1 (R = 0.9942). The limits of detection (LOD) and quantification (LOQ) were 0.3 and 0.8 nmol L−1, respectively. Real samples were also investigated, with recovery values of 96.0% and 108.3% obtained for tomato and pond water samples, respectively. The proposed sensor is a feasible option for malathion detection, offering a linear response, good sensitivity, and a low detection limit. View Full-Text
Keywords: magnetic iron particles; organophosphorus pesticides; acetylcholinesterase; malathion magnetic iron particles; organophosphorus pesticides; acetylcholinesterase; malathion

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Rodrigues, N.F.M.; Neto, S.Y.; Luz, R.C.S.; Damos, F.S.; Yamanaka, H. Ultrasensitive Determination of Malathion Using Acetylcholinesterase Immobilized on Chitosan-Functionalized Magnetic Iron Nanoparticles. Biosensors 2018, 8, 16.

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