Aptamer-functionalized magnetic nanoparticle-based bioassay for the detection of ochratoxin a using upconversion nanoparticles as labels

摘要

A sensitive luminescent bioassay for the detection of ochratoxin A (OTA), a small molecularnmycotoxin, was developed using aptamer-conjugated magnetic nanoparticles (MNPs) as thenrecognition and concentration element and upconversion nanoparticles (UCNPs) as highly sensitivenlabels. The bioassay system was fabricated by immobilizing aptamer DNA 1 sequence onto the surfacenof Fe3O4 MNPs, which were implemented to capture and concentrate OTA from bulk samples. Thenaptamer DNA 1 sequence then hybridized with UCNPs modified with DNA 2 sequence, which couldndissociate from DNA 1 and result in a decreased luminescent signal when aptamer DNA 1 recognizednand bound to target OTA. Under the optimal conditions, the decreased luminescent intensity (DI) isnproportional to the concentration of OTA in the range of 1 u0001 10u000313 to 1 u0001 10u00039 g mLu00031 with a detectionnlimit of 1 u0001 10u000313 g mLu00031. The proposed method then was successfully applied to measure OTA innnaturally contaminated maize samples and validated by a commercially available enzyme-linkednimmunosorbent assay (ELISA) method. Benefiting from the magnetic separation and concentrationneffect of MNPs, the high sensitivity of UCNPs, as well as the selectivity and stability of the aptamer, thenpresent upconversion luminescent bioassay offers a promising approach for the screening of smallnmolecular mycotoxins because it is simple, rapid, highly sensitive, specific, does not require sample preconcentrationnand lacks interference from autofluorescence of other biomolecules.