A FRET-based dual-color evanescent wave optical fiberaptasensor for simultaneous fluorometric determination of aflatoxin M1 and ochratoxin A.

Abstract

A dual-color fluorescence resonance energy transfer (FRET) based aptasensor is described for simultaneous determination of the mycotoxins aflatoxin M1 (AFM1) and ochratoxin A (OTA). Aptamers against AFM1 and OTA were labeled with two fluorophores with different excitation wavelengths (Cy5.5; 675nm; and Alexa 405; 401nm), respectively. They were used as the signalling probes. A compact dual-color evanescent wave all-fiber detection system with two lasers (635nm; red; and 405nm; purple) was used for the simultaneous collection of two-wavelength fluorescence signals. The hybridization of labeled aptamers with complementary sequences (Q-cDNA) labeled with adarkquencher (BHQ3or dabcyl)causes fluorescence to be strongly reduced because of the fluorescence resonance energy transfer. In the presence of AFM1 and OTA, they bind to their respective aptamer and result in the dissociation of double stranded DNA, which induce fluorescence recovery. Under the optimum conditions, AFM1 and OTA can simultaneously and selectively be determined ranged from 1ng·L-1 to 1mg·L-1. The detection limits of AFM1 and OTA are 21 and 330ng·L-1, respectively (S/N = 3). The FRET-based dual-color detection scheme was applied to the simultaneous detection of AFM1 and OTA in milk with good recovery, precision, and accuracy. Graphical abstract Aptamers against AFM1 and OTA were labeled with two fluorophores with different excitation wavelengths (Cy5.5; 675nm; and Alexa 405; 401nm) and then used assignalling probes. A FRET-based aptasensor is described for simultaneous determination of AFM1 and OTA using dual-color evanescent wave system with two lasers (635nm; red; and 405nm).