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Simple and Fast Picomolar Detection of Ochratoxin A Using a Reusable Label Free Aptasensor Built with a Layer-by-layer Procedure

Year: 2017

Journal: Electroanalysis, Volume 29, OCT, page 2268–2275

Authors: Simao, Estefani P.; Cao-Milan, Roberto; Costa-Pedro, Graciela; De Melo, Celso P.; Cao, Roberto; Oliveira, Maria D. L.; Andrade, Cesar A. S.

Organizations: Brazilian National Council for Scientific and Technological Development [CNPq 490184/2011-1, 302885/2015-3, 302930/2015-9]; Pernambuco State Foundation for Research Support (FACEPE); PROPESQ/UPFE; CNPq

Keywords: 1, Aptamer 2; Aptasensor 3; Ochratoxin A 4; Impedimetric sensor 5; Layer-by-Layer

A label free impedimetric aptasensor for simple, fast and reusable picomolar detections of Ochratoxin A (OTA) in grape juices was designed. Two main factors were observed to affect the accurate detections of the toxin: i-lateral interactions between self-assembled aptamers ii- adsorption of large molecules present in complex matrixes like grape juices. Lateral interactions between aptamers were minimized by constructing the aptasensor in a Layer-by-Layer procedure. The interferences associated to the unspecific and irreversible adsorption of large molecules present in grape juice, were reduced by submitting samples to ultrafiltration prior to analysis. With this protocol, a 0.12pM limit of detection and 0.24pM limit of quantification in spiked grape juices were achieved after only 5-7mins of interaction with the samples. The presented aptasensor can be recovered after a simple immersion in hot water (90 degrees C) for ten minutes.