title: Label-free impedimetric aptasensor for ochratoxin-A detection using iridium oxide nanoparticles.
abstract: In this article, a novel aptasensor for ochratoxin A (OTA) detection based on a screen-printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles (IrO2 NPs) is presented. The electrotransducer surface is modified with an electropolymerized film of PTH followed by the assembly of IrO2 NPs on which the aminated aptamer selective to OTA is exchanged with the citrate ions surrounding IrO2 NPs via electrostatic interactions with the same surface. Electrochemical impedance spectroscopy (EIS) in the presence of the [Fe(CN)6](-3/-4) redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of OTA in a range between 0.01 and 100 nM, obtaining one of the lowest limits of detection reported so far for label-free impedimetric detection of OTA (14 pM; 5.65 ng/kg). The reported system also exhibits a high reproducibility, a good performance with a white wine sample, and an excellent specificity against another toxin present in such sample.
authors.affiliation: ‡Departament de Química, Universitat Autònoma de Barcelona, 08193, Bellaterra (Barcelona), Spain.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Rivas
authors.forename: Carmen C
authors.initials: CC
authors.lastname: Mayorga-Martinez
authors.forename: Daniel
authors.initials: D
authors.lastname: Quesada-González
authors.forename: Alejandro
authors.initials: A
authors.lastname: Zamora-Gálvez
authors.forename: Alfredo
authors.initials: A
authors.lastname: de la Escosura-Muñiz
authors.affiliation: §ICREA - Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain.
authors.forename: Arben
authors.initials: A
authors.lastname: Merkoçi
mesh_terms: D052157:Aptamers, Nucleotide / Q000378:metabolism*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D017097:Electric Impedance; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D007495:Iridium / Q000737:chemistry*; D057230:Limit of Detection; D053758:Nanoparticles; D009793:Ochratoxins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D010640:Phenothiazines / Q000737:chemistry; D058105:Polymerization
chemical_list: D052157:Aptamers, Nucleotide; D009793:Ochratoxins; D010640:Phenothiazines; C044458:iridium oxide; C025589:ochratoxin A; D007495:Iridium; D002244:Carbon; C009469:thionine