MicroRNA Triggered\nDimerization of DNA Tetrahedron\nfor Enhanced Biosensing Performance of Solid-State Nanochannels\nFunctionalized with MoS<sub>2</sub> Nanosheets

Solid-state nanochannels (SSN) have great development\npotential\nas a biosensing interface. The integration of two-dimensional nanomaterials\nwith nanochannels endows SSN with diverse properties, including distinguishing\nDNA nanostructures. In this study, by modifying MoS<sub>2</sub> nanosheets,\nthe outer surface of SSN could be endowed with robust adsorption properties\nfor single-stranded DNA. Therefore, DNA tetrahedrons connected with\nsingle-stranded DNA could remain on the SSN surface, whereas DNA tetrahedron\ndimers with full double-stranded structures formed by the presence\nof target microRNA cannot be retained on the surface of nanochannels.\nThe change in the DNA nanostructure generated by the target recognition\nprocess could cause variations of steric hindrance and electrostatic\nrepulsion on the surface of the SSN. The variations were reflected\nby the free diffusion flux of [Fe(CN)<sub>6</sub>]<sup>3–</sup>. Then, the sensitive electrochemical detection method for microRNA\nwas established, and the detection limit of the method for microRNA-31\nwas as low as 0.5 fM. The study provided a promising approach for\nthe ultrasensitive detection of biomarkers, thereby offering potential\nmeans for early diagnosis of the related diseases.