Gold Nanoparticle-Based Fluorescence Resonance Energy Transfer Aptasensor for Ochratoxin A Detection

Abstract

In this paper, a sensitive and specific fluorescence resonance energy transfer (FRET) aptasensor for the detection of Ochratoxin A (OTA) was developed based on a dye-tagged ssDNA hybridized with aptamer-conjugated Au nanoparticles (Au NPs). The binding between the aptamer-Au NPs conjugate and the dye-labeled ssDNA leads to the fluorescence quenching of FAM due to its close proximity. The addition of OTA results in fluorescence recovery, attributed to the formation of a quadruplex-OTA complex, which detaches from the surface of Au NPs. Under optimal conditions, the relative fluorescence intensity (ΔI) is proportional to the concentration of the OTA in the range of 5 × 10⁻¹² to 5 × 10⁻⁹ g/mL, with a detection limit of 2 × 10⁻¹² g/mL. The proposed method was successfully applied to measure the concentration of OTA in naturally contaminated maize samples and validated using a commercially available enzyme-linked immunosorbent assay (ELISA) method. This work demonstrates that the combination of an aptamer that has a high binding affinity for the analyte with highly sensitive Au NPs that undergo FRET is a promising approach for the detection of small molecule toxins.

Keywords:

• Aptamer
• Au nanoparticles
• FRET
• Ochratoxin A

Acknowledgments

This work was partly supported by the “863” project (2008AA10Z419), Science and Technology Supporting Project of Jiangsu Province (BE2010679, SBE201170933), Universities Independent Research Program of MOE (JUSRP31003), sklf-kf-201112, and 111 project-B07029.