Development of a DNA-based biosensor for the fast and sensitive detection of ochratoxin A in urine.

Development of a DNA-based biosensor for the fast and sensitive detection of ochratoxin A in urine.
Anal Chim Acta. 2020 Oct 09;1133:20-29
Authors: Santovito E, Greco D, D'Ascanio V, Sanzani SM, Avantaggiato G
Abstract
In this paper, a novel DNA-based biosensor is proposed, which is based on paramagnetic microbeads carrying an ochratoxin A (OTA) capture aptamer. A sandwich-like detection complex is linked to the capture aptamer and is able to trigger, in presence of OTA, an isothermal rolling circle amplification (RCA) reaction. This latter generated autocatalytic units with a peroxidase activity (DNAzyme) that, in presence of a proper substrate, gave a blue-coloured product visible by the naked eye. The capture aptamer, blocked onto magnetic beads, allowed the specific capture of OTA in liquid samples. The modified detection aptamer, annealed to a circularized probe, was then used to detect the toxin capture event. Indeed, in the presence of OTA and an isothermal enzyme, the circular DNA was amplified, producing a single-stranded and tandem repeated long homologous copy of its sequence. In the DNA strand, a self-catalytic structure was formed with hemin as the catalytic core, inducing the development of blue colour in the presence of ABTS and hydrogen peroxide. The results showed that the biosensor has high sensitivity and selectivity for the detection of OTA, as low as 1.09 × 10-12 ng/mL. Moreover, the proposed biosensor was su...

Source: Analytica Chimica Acta - October 1, 2020 Category: Chemistry Authors: Santovito E, Greco D, D'Ascanio V, Sanzani SM, Avantaggiato G Tags: Anal Chim Acta Source Type: research