Selection of DNA Aptamers Against Botulinum Neurotoxin E for Development of Fluorescent Aptasensor

Botulinum neurotoxins (BoNTs) produced by Clostridium botulinum are the deadliest toxins known to mankind with a potential of possible bioterrorism agents. Due to the high-potential harm of these toxins, a sensitive and real-time monitoring capable detection systems are required for the early stage detection. In this study, a novel sol–gel-based SELEX was used to isolate single-stranded nucleic acids (ssDNA) aptamers against purified BoNT type E toxoid (BoNTE) using a chemically synthesized random N40 ssDNA library. The bound aptamer sequences after five rounds were analyzed using next-generation sequencing and the resulted high-frequency aptamers were characterized using biolayer interferometry. Among the tested, aptamer BT5.6 showed low nanomolar binding affinity (KD, 53.3 nM) toward BoNTE. As a proof of concept, the aptamer was utilized in a graphene oxide-based detection platform. In summary, we screened and identified a ssDNA aptamer with high affinity toward BoNTE, which, we believe can be used for development of sensitive detection systems.