An electrochemical competitive biosensor for ochratoxin A based on a DNA biotinylated aptamer.
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 0.78-8.74 ng mL(-1) and a limit of detection of 0.07±0.01 ng mL(-1), and was accurately applied to extracts of certified and spiked wheat samples with an RSD lower than about 8%.
Institute of Environmental Sciences (IUCA), University of Zaragoza, Zaragoza, Spain.
Laura
L
Bonel
Juan C
JC
Vidal
Patricia
P
Duato
Juan R
JR
Castillo
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D019921:Biotinylation; D055664:Electrochemical Techniques / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D057230:Limit of Detection; D008280:Magnetics / Q000379:methods; D009183:Mycotoxins / Q000032:analysis*; D009793:Ochratoxins / Q000032:analysis*; D014908:Triticum / Q000737:chemistry*
D052157:Aptamers, Nucleotide; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A