A fluorescence immunosensor for ochratoxin A based on resonance energy transfer between fluorescein derivative and gold nanoparticles

Abstract

The detection of ochratoxin A (OTA), a harmful toxic contaminant of foods causing serious health problems, is of great importance. Common analytical methods for this purpose are expensive, time- and labor-consuming. To overcome these limitations, a fluorescence resonance energy transfer (FRET)-based immunosensor for the detection of ochratoxin A (OTA) was designed using fluorophore (amino-methyl fluorescein, AMF) and gold nanoparticles (AuNPs) as an energy donor and acceptor, respectively. The sensing principle is based on the recording of recovered OTA-AMF fluorescence due to competitive immunoreaction between free OTA and OTA-AMF for binding to anti-OTA antibodies labeled with AuNPs. Under optimal sensing conditions, a linear correlation was obtained between the intensity of OTA-AMF fluorescence and the concentration of OTA in the range of 0.09 – 3.12 ng/mL with a detection limit of 0.02 ng/mL. The proposed fluorescence immunosensor has been successfully validated by analyzing wheat and wine samples with recovery ranging from 70.8 % to 115.8 % and a relative standard deviation of less than 10 %. This work demonstrates a rapid and easy-to-use sensing platform based on the antigen-antibody-mediated FRET process in the AMF-AuNP donor-acceptor pair.