Aptamer is a single-stranded oligonucleotide that recognizes and bind to the specific target of intend with quasi-affinity to antibody. As decent recognition probe, aptamer has been recognized as receptor with various sensing platform to monitor the specific target in the environment. PFOA, PFOS, and verrucarin A were chosen for the target compounds to isolate single-stranded DNA aptamer to show the applicability of aptamer-based sensor (aptasensor) at the environment. As primary compounds of per- and polyfluoroalkyl substances (PFAS), PFOA and PFOS are contaminants of emerging concern due to the potential of chronic toxicity and the nature of recalcitrant to degradation. Verrucarin A, a representative of type D trichothecene, is a mycotoxin that could be secreted by molds causing damp building-related illness. Therefore, the reliable sensing technologies are required to manage the safe quality of environment by consistently monitoring at the point-of-need. In this study, the isolated aptamers that could bind to PFOA, PFOS, and verrucarin A after iterative in-vitro procedure, called SELEX, showed binding affinity of K_D 5.5 μM, 6.76 μM, and 29.47 nM, respectively. The specificity of aptamer toward PFOS and verrucarin A was greatly enhanced to that of aptamer toward PFOA after applying counter-SELEX to remove any sequences that may bind to structurally similar compounds. The binding mechanism had been elucidated with different approach for each aptamers using NMR, homology analysis, and in-silico method. Finally, the feasibility of aptasensor was assessed and compared to show the potential of broad applications with various transducers, where the most of the developed sensors are limited to specific transducing platform. The developed electrochemical and fluorescence-based aptasensors demonstrated different detection ranges from nanomolar to micromolar range and may therefore be effectively employed at the point-of-care to monitor environmentally relevant levels at the locations where the detection levels are variable.

Jong Kwon Choe

Seoul National University

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