Selection of Highly Specific DNA Aptamer for the Development of QCM‐Based Arsenic Sensor

Abstract Heavy metal arsenic is a water pollutant that affects millions of lives worldwide. A novel aptamer candidate for specific and sensitive arsenic detection was identified using Graphene Oxide‐SELEX (GO‐SELEX). Eleven rounds of GO‐SELEX were performed to screen As(III) specific sequences. The selected aptamer sequences were evaluated for their binding affinity. The dissociation constant of the best aptamer candidate, As‐06 was estimated by fluorescence recovery upon target addition, and it was found to be 8.15 nM. A QCM‐based biosensing platform was designed based on the target‐triggered release of aptamer from the QCM electrode. An rGO‐SWCNT nanocomposite was adsorbed on the gold surface, and the single‐stranded probe was stacked on the rGO‐CNT layer. Upon addition of the target to the solution, a concentration‐dependent release of the ssDNA probe was observed and recorded as the change in the electrode frequency. The developed QCM sensor showed a dynamic linear range from 10 nM to 100 nM and a low detection limit of 8.6 nM. The sensor exhibited excellent selectivity when challenged with common interfering anions and cations.