Development of an aptasensor based on a fluorescent particles-modified aptamer for ochratoxin A detection.

The presented work reports a generic fluorescent aptasensing design employing carboxy-modified fluorescent particles as a signal-generating probe and magnetic particles as a solid separation support. Carboxy-modified fluorescent particles were used to modify the aptamer and act as a signal-generating probe. Magnetic beads were used as an immobilization surface to perform the function of a solid separation support. As a proof of concept, the assay was used to detect ochratoxin A (OTA). Fluorescent detection based on the displacement and competition format was performed, and the obtained results were compared. The competition-based assays were characterized with improved analytical characteristics as compared to those based on the displacement principle. The competitive fluorescent assays showed a high sensitivity where the detection limit and IC50 were 0.005 and 7.2 nM respectively. The aptasensing platform was finally demonstrated for the detection of OTA in a beer sample. However, this is a generic approach that can be very easily extended to other matrixes to determine OTA. Additionally, the proposed concept of fluorescent particles as a signal-generating probe in combination with magnetic particles can also be integrated to other fluorescent-based affinity assays.