Nature's great repository provides nucleic acids and amino acids as the fundamental elements of life. Inspired by the programmability of nucleic acids, DNA nanotechnology has been extensively developed based on the strand displacement reaction of nucleic acids. In comparison with nucleic acids, amino acids possess higher programmability and more functionalities owing to the diversity of the amino acid unit. However, the design of the peptide-based bimolecular cascade is still limited. We herein describe a peptide-based strand displacement reaction, which was granted with a specific biological function by addition of a functional domain onto the coiled-coil peptide based displacement substrate. The displacement substrate was specifically designed to response to Tau protein based on a well-established Tau inhibition sequence. We demonstrated that the kinetics of the designed displacement reaction can be dynamically tuned through blocking the toehold region to prevent migration. A nanomolar Tau detection linear range was achieved through the designed displacement reaction within a rapid turnaround time of 30 min. We also presented the capability of the peptide strand displacement based sensing system operating in real human biological samples and its excellent orthogonality on response to irrelevant biological components. We envision that this will be of especially high utility for the development of next-generation biotechnology.
Keywords: Tau detection; biomolecular motor; coiled-coil; electrochemical biosensor; peptide displacement reaction.