Selection and characterization of toxic <i>Aspergillus</i> spore-specific DNA aptamer using spore-SELEX

Abstract

As airborne spores of toxic <i>Aspergillus</i> species cause mild symptoms to invasive fungal infections, their indoor concentration should be controlled through real-time management. Aptamer-based biosensors could provide economical and simple solutions for point-of-care. In this study, we isolated aptamers binding to the spores of three representative toxic <i>Aspergillus</i> species (<i>A. fumigatus</i>, <i>A. flavus</i>, and <i>A. niger</i>) for the first time, using cell-SELEX (systematic evolution of ligands through exponential enrichment). Among the aptamer candidates, Asp-3 showed a broad and high binding affinity for the <i>Aspergillus</i> spores. Considering the low binding affinity with proteinase-treated spores, we speculated that the Asp-3 binding sites could be possibly associated with cell surface proteins. The high Asp-3 specificity was confirmed by comparing the binding affinity between the <i>Aspergillus</i> target species and other common indoor fungal species. Moreover, we also established quantitative linear relationships between Asp-3 and the spore concentration of each <i>Aspergillus</i> species. Therefore, the selected Asp-3 aptamer, conjugated with detection sensors, could be an effective biorecognition element for the spores of three toxic <i>Aspergillus</i> species.