Aptamer-based biosensor for label-free detection of ethanolamine by electrochemical impedance spectroscopy

• Label-free aptamer DNA sensor is developed for EA detection.
• Aptamer switches to G-quadruplex on the electrode, offering the binding site of EA.
• CD and EIS confirm the sensing mechanism.
• The sensor exhibits excellent selectivity and high sensitivity.
• The sensor is successfully challenged in serum and tap water samples.

A label-free sensing assay for ethanolamine (EA) detection based on G-quadruplex-EA binding interaction is presented by using G-rich aptamer DNA (Ap-DNA) and electrochemical impedance spectroscopy (EIS). The presence of K+ induces the Ap-DNA to form a K+-stabilized G-quadruplex structure which provides binding sites for EA. The sensing mechanism was further confirmed by circular dichroism (CD) spectroscopy and EIS measurement. As a result, the charge transfer resistance (RCT) is strongly increased as demonstrated by using the ferro/ferricyanide ([Fe(CN)6]3−/4−) as a redox probe. Under the optimized conditions, a linear relationship between ΔRCT and EA concentration was obtained over the range of 0.16 nM and 16 nM EA, with a detection limit of 0.08 nM. Interference by other selected chemicals with similar structure was negligible. Analytical results of EA spiked into tap water and serum by the sensor suggested the assay could be successfully applied to real sample analysis. With the advantages of high sensitivity, selectivity and simple sensor construction, this method is potentially suitable for the on-site monitoring of EA contamination.

Figure optionsDownload as PowerPoint slide