title: Highly sensitive ochratoxin A impedimetric aptasensor based on the immobilization of azido-aptamer onto electrografted binary film via click chemistry.
abstract: The aptamer immobilization onto organized mixed layers of diazonium salts via click chemistry was explored. The immobilized aptamer was employed in the fabrication of a highly sensitive and reusable electrochemical impedimetric aptasensor for the detection of ochratoxin A (OTA). The screen-printed carbon electrodes (SPCEs) were first modiﬁed by electrografting of a protected 4-((trimethylsilyl)ethynyl) benzene (TMSi-Eth-Ar) layer followed by a second one of p-nitrobenzene (p-NO(2)-Ar) by means of electrochemical reduction of their corresponding diazonium salts, (TMSi-Eth-Ar-N(2)(+)) and (p-NO(2)-ArN(2)(+)). After deprotection, a layer with active ethynyl groups was obtained. In the presence of copper (I) catalyst, the ethynyl groups reacted efficiently with aptamer bearing an azide function, thus forming a covalent 1,2,3-triazole linkage. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of ferri/ferrocyanide redox probe [Fe(CN)(6)](4-/3-) were used to characterize each step in the aptasensor development. The increase in electron-transfer resistance (R(et)) values due to the speciﬁc aptamer-OTA interaction was proportional to the concentration of OTA in a range between 1.25 ng/L and 500 ng/L, with a detection limit of 0.25 ng/L.
authors.affiliation: BIOMEM, Université de Perpignan, 52 Avenue Paul Alduy, 66860 Perpignan Cedex, France.
authors.forename: Akhtar
authors.initials: A
authors.lastname: Hayat
authors.forename: Audrey
authors.initials: A
authors.lastname: Sassolas
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Marty
authors.forename: Abd-Elgawad
authors.initials: AE
authors.lastname: Radi
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D001515:Beer / Q000032:analysis; D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D057930:Click Chemistry; D058266:Dielectric Spectroscopy; D004566:Electrodes; D009793:Ochratoxins / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D001386:Azides; D009793:Ochratoxins; C025589:ochratoxin A; D002244:Carbon