Development Of Nanopore Sensor By Utilization Of 3D Nucleic Acid Nanostructures As Signal Transduction Carrier

Nanopore sensors have been widely used in single molecule detection,but it is very challenging to prepare nanopores that match the target molecules.Especially when the size of the target molecules is relatively small,it is difficult to obtain nanopores with ideal pore size.If a new detection scheme of solid-state nanopore sensor can be developed,so that the aperture of nanopore sensor no longer needs to match the size of the target molecules,the application of nanopore sensor can be further expanded.This paper proposes a scheme to convert the detection of target molecules into controllable nanostructure detection to solve the above problems.Using single stranded nucleic acid to synthesize controllable nanostructures through certain "programming" means is an important idea and means to solve this problem.The reasons are as follows: the size and morphology of nucleic acid nanostructures are accurately controllable;The signal-to-noise ratio of electrical signals generated by nucleic acid nanostructures through nanopore detection is very high,which can shield non-specific electrical signals in complex samples;Combined with nucleic acid nanostructure,it has stronger expansibility and can be extended to detect multiple objects.Through the study and comparison of a series of pore signals of different nucleic acid nanostructures,it is found that the nucleic acid tetrahedron has a strong signal-to-noise ratio.In Chapter 2,we combined nucleic acid tetrahedron with CRISPR-Cas system to develop a new detection method to detect the nucleic acid fragment of HPV virus.HPV18 virus infection can lead to cervical epithelial lesions and even cancer.In this new detection method,we transform the detection of target fragment DNA into the detection of nucleic acid tetrahedron,and amplify the signal through CRISPR-Cas12 system.Thus,the detection of HPV18 DNA fragments is realized through glass nanopores.The detection limit of this method is 3 n M,the detection range is 0.5 ? 50 n M,and the linear range is 0.5 ? 10 n M.The size and shape of nucleic acid nanostructures can affect their ability as signal transduction carriers.In order to construct better nucleic acid nanostructures as signal transduction carriers,cubic nucleic acid nanostructures and their corresponding via electrochemical characteristics were further explored in Chapter 3.Compared with other nucleic acid nanostructures,such as nucleic acid triangular prism and nucleic acid nano barrel,the translocation through the pore of nucleic acid cube has high signal-to-noise current blockades,strong stability and reproducibility.At the same time,the change of nucleic acid cube structure has a great impact on its translocation signal.Systematic studies have shown that the translocation signal of nucleic acid cube can be affected by controlling the temperature,adjusting the size or integrity of the structure,and functionalizing the structure.The combination of nucleic acid cube structure and nanopore sensor has many potential applications.We preliminarily explored the feasibility of detecting mercury ions.