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

Here, we report a convenient and highly sensitive sandwich electrochemical sensor based on a new conception of bivalent split aptamer signal probe (for example S2D1S2), which is readily engineered through a simple hybridization of two identical monovalent split aptamers (S2) to a DNA template strand (D1). Because of the bivalence cooperativity enhanced sandwich binding to target molecules, this type of DNA-scaffolded bivalent signal probe exhibits significantly improved signal increase (SI) for sandwich electrochemical detection of target molecules in comparison with the conventional monovalent counterparts (S1). [Display omitted] •Bivalent enhancement was employed to design split aptamer probe with high affinity.•Bivalent split aptamer (BSA) probe was engineered through one-step hybridization.•BSA signal probe was used to construct sensitive sandwich electrochemical sensors. 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.