Abstract
High affinity DNA aptamers against anatoxin-a (ATX), the smallest potent neurotoxin (Mol. Wt, 165.23Da) were selected and identified in vitro using the systematic evolution of ligands by exponential enrichment (SELEX) approach. Aptamers with dissociation constants (Kd) of nanomolar range were isolated. The aptamer sequence of highest affinity was used to design a label-free impedance based aptasensor to assay ATX, for which there are no reported biosensors so far. The aptamer self assembled monolayer is formed on a gold electrode using the disulfide modified aptamer. The assembly process of the aptasensor was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Upon ATX binding to the immobilized aptamer, a significant decrease in the electron-transfer resistance was observed as a result of the aptamer conformation change, which is used as the sensor signal. The aptasensor showed a limit of detection of 0.5nM and a wide linear range for ATX concentrations between 1nM and 100nM. The Kd of anti–ATX aptamer was calculated by electrochemical methods as well as the fluorescence. Interestingly, the Kd that was calculated from the aptasensor signal showed a lower value implying that the anchoring of the aptamer on the Au surface enhanced its affinity to ATX. The ATX aptasensor showed high stability as well as high specificity against common cynaobacterial toxins. Further development of biosensors that use anatoxin-a binding aptamers as a new recognition receptors could provide potential alternatives to the traditional assays for fast and simple monitoring of anatoxin-a.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.