title: Ultra-sensitive conductometric detection of pesticides based on inhibition of esterase activity in Arthrospira platensis.
abstract: Enzymatic conductometric biosensor, using immobilized Arthrospira platensis cells on gold interdigitated electrodes, for the detection of pesticides in water, was elaborated. Cholinesterase activity (AChE) was inhibited by pesticides and a variation of the local conductivity was measured after addition of the substrate acetylthiocholine chloride (AChCl). The Michaelis-Menten constant (Km) was evaluated to be 1.8 mM through a calibration curve of AChCl. Inhibition of AChE was observed with paraoxon-methyl, parathion-methyl, triazine and diuron with a detection limit of 10(-18) M, 10(-20) M, 10(-20) M and 10(-12) M, respectively and the half maximal inhibitory concentration (IC50) was determined at 10(-16) M, 10(-20) M, 10(-18) M and 10(-06) M, respectively. An important decrease of response time τ90% was recorded for AChE response towards AChCl after 30 min cell exposure to pesticides. Scanning electron microscopy images revealed a degradation of the cell surface in presence of pesticides at 10(-06) M.
authors.affiliation: University of Lyon, Institut des Sciences Analytiques, CNRS/ENS/UCBL UMR 5280, 69100 Villeurbanne, France. tekayanadeje@yahoo.fr
authors.forename: Nadèje
authors.initials: N
authors.lastname: Tekaya
authors.forename: Olga
authors.initials: O
authors.lastname: Saiapina
authors.forename: Hatem
authors.initials: H
authors.lastname: Ben Ouada
authors.forename: Florence
authors.initials: F
authors.lastname: Lagarde
authors.forename: Hafedh
authors.initials: H
authors.lastname: Ben Ouada
authors.forename: Nicole
authors.initials: N
authors.lastname: Jaffrezic-Renault
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D002800:Cholinesterase Inhibitors / Q000032:analysis* / Q000633:toxicity; D003217:Conductometry / Q000379:methods*; D000458:Cyanobacteria / Q000187:drug effects* / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D057230:Limit of Detection; D010575:Pesticides / Q000032:analysis* / Q000633:toxicity
chemical_list: D002800:Cholinesterase Inhibitors; D010575:Pesticides; D000110:Acetylcholinesterase