An electrochemical competitive biosensor for ochratoxin A based on a DNA biotinylated aptamer

  • Bonel L
  • Vidal J
  • Duato P
 et al. 
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Ochratoxin A (OTA) is one of the most important mycotoxin contaminants of foods, particularly cereals and cereal products, with strict low regulatory levels (of ppb) in many countries worldwide. An electrochemical competitive aptamer-based biosensor for OTA is described. Paramagnetic microparticle beads (MBs) were functionalized with an aptamer specific to OTA, and were allowed to compete with a solution of the mycotoxin conjugated to the enzyme horseradish peroxidase (OTA-HRP) and free OTA. After separation and washing steps helped with magnetic separations, the modified MBs were localized on disposable screen-printed carbon electrodes (SPCEs) under a magnetic field, and the product of the enzymatic reaction with the substrate was detected with differential-pulse voltammetry. In addition to magnetic separation assays, other competitive schemes (direct/indirect aptasensors performed on the SPCEs surface or using gold nanoparticles functionalized with the aptamer) were preliminary tested, optimized and compared. The magnetic aptasensor showed a linear response to OTA in the range 0.78-8.74ngmL-1and a limit of detection of 0.07±0.01ngmL-1, and was accurately applied to extracts of certified and spiked wheat samples with an RSD lower than about 8%. © 2010 Elsevier B.V.

Author-supplied keywords

  • Aptamer
  • Electrochemical biosensor
  • Mycotoxins
  • Ochratoxin A
  • Screen printed

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  • Laura Bonel

  • Juan C. Vidal

  • Patricia Duato

  • Juan R. Castillo

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