Reusable, label-free electrochemical aptasensor for sensitive detection of small molecules

摘要

We report a sensitive electrochemical aptasensor for adenosine based on electrochemical impedance spectroscopy measurement, which gives not only a label-free but also a reusable platform to make the detection of small molecules simple and convenient. Since screened through the systematic evolution of ligands by exponential enrichment (SELEX) process from random RNA or DNA libraries, aptamers have been widely used in analytical assays and shown their enormous potential in recognizing and detecting various targets due to their generally impressive selectivity, affinity and their multifarious advantages over the traditional recognition elements. As it was especially difficult to find a specific recognizing element for small molecules, aptamers from in vitro SELEX did possess considerable advantages in analytical assays for small molecules. Up to now, many aptamer-based methods have been used for small molecules, such as fluorescence, colorimetry and electrochemistry. Though all the methods developed could realize the small molecule detection successfully, some common disadvantages could not always be avoided. First, most of the existing methods required the step of labeling the probes onto the ssDNA molecules or the targets. Such a labeling process would not only make experiments relatively complex and expensive, but also affect the binding affinity between the targets and their aptamers to a greater or lesser degree. Secondly, many of the sensing systems rely on the conformational change of the aptamers after binding with their targets, therefore the application was obviously limited. Furthermore, many of the sensing systems were not reusable after detection, which increased the complication of operation.