Применение наночастиц золота для высокочувствительного поляризационного флуоресцентного аптамерного анализа охратоксина А

The use of gold nanoparticles ( GNPs ) as carriers for the decreasing of detection limit of fluorescence polarization ( FP ) aptamer assay is proposed. The common FP assay is based on the use of polarized exciting light and changes in the polarization of emitted light by the fluorophore-analyte conjugate before and after its binding with a receptor of the target analyte. Aptamers application as receptors in this assay is limited due to their low molecular weight and corresponding low influence on polarization of emitted light. This limitation may be overcome by the inclusion of aptamers in larger intermolecular complexes. In the present work, the advantages of GNPs as unified, stable and simply modified carriers for aptamers are demonstrated. The FP aptamer assay was realized with the use of GNPs with average diameter of 8.7 nm and ochratoxin A ( OTA ) as target analyte. Finally the assay was tested for OTA control in spiked white wine. The reached limit of detection was 2.3 µg/kg being 25-fold lower as compared to native aptamer. Time of the assay is 15 min. The universality of the proposed approach makes it possible to use aptamers for FP assay of various low molecular weight substances.