Highly sensitive sandwich electrochemical sensor based on DNA-scaffolded bivalent split aptamer signal probe

Split aptamers find growing interest as recognition elements for sandwich electrochemical sensors. Here, we report a convenient and highly sensitive sandwich electrochemical sensor based on a new conception of bivalent split aptamer signal probe, which is readily engineered through a simple hybridization of two identical monovalent split aptamers to a DNA template strand. Because of the bivalence cooperativity enhanced sandwich binding to target molecules, this type of DNA-scaffolded bivalent signal probe exhibits significantly increased signal gain for sandwich electrochemical detection of target analytes in comparison with the conventional monovalent signal probe. Through rational optimization of the length of anchor duplex in DNA scaffold and concentration of bivalent signal probe in electrochemical test solution, high signal sensitivity for ATP detection is achieved with a detection limit of 41 nM. The DNA-scaffolded bivalent signal probe based sandwich electrochemical sensor is also specific, selective and applicable for ATP detection in real samples. Due to its simplicity in design and high sensitivity for target recognition, we hope that the conception of DNA-scaffolded bivalent signal probe will provide a useful guide to further developing split aptamer-based sandwich electrochemical sensors for a wide variety of other target analytes.