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DNA aptamers selection and characterization for development of label-free impedimetric aptasensor for neurotoxin anatoxin-a by Reda Elshafey; Mohamed Siaj; Mohammed Zourob is a Engineering article available to read on EtoBox.

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High affinity DNA aptamers against anatoxin-a (ATX), the smallest potent neurotoxin (Mol. Wt, 165.23 Da) 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 0.5 nM and a wide linear range for ATX concentrations between 1 nM and 100 nM. 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 si

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Author

Reda Elshafey; Mohamed Siaj; Mohammed Zourob

Publisher

Elsevier Science; Elsevier ; Elsevier Ltd.; Elsevier BV (ISSN 0956-5663)

Published

2015

Language

EN

Field

Engineering (Physical Sciences)