Fluorescence Aptasensor Development for Aflatoxin B1

Using a previously selected and characterized aptamer (known as 3MR5) for aflatoxin B1 (AFB1), a Förster Resonance Energy Trandfer (FRET) based optical biosensor for AFB1 was constructed. Experiments were conducted utilising the organic chromophores Fluorescein (FAM) and Black Hole Quencher 1 (BHQ1) that had been incorporated into a complementary oligonucleotide sequence or capture probe (RCP), and the 3MR5 sequence, respectively. Fluorescence experiments were conducted and it was discovered that no recovery of fluorescence occurred after addition of AFB1 and so an alternative FRET pair was tested. This new FRET pair was that of 525 nm emitting Quantum Dots (QDs) and spherical gold nanoparticle (AuNPs). Hybridization of RCP conjugated QDs and 3MR5 conjugated AuNPs resulted in the quenching of the QD fluorescence, however addition of AFB1 did not result in any recovery of fluorescence. Potential causes for this lack of fluorescence recovery are discussed.