Design And Construction Of Magnetic Tweezers System For DNA Deceleration In Nanopore

At present,nanopore-based third-generation genetic testing techniques are the most likely achieving the normalizing process of diagnosis and treatment of genetic diseases.To solve the problem,design a magnetic tweezers device.The magnetic tweezers is an effective means of controlling the speed of DNA.The structure of this paper is follows:?1?The magnetic tweezers instrument was designed for the purpose of controlling the velocity of DNA in the nanopore.The finite element analysis programs was used to simulate the magnetic field distribution,and the magnetic beads were subjected to force analysis,ensure that the magnetic field can overcome the electric field force of the DNA on the magnetic beads.And built a magnetic cymbal control system-based on probe station,including magnetic circuit system,patch champ,micromanipulator,CCD imaging system,liquid pool,Faraday cage,damping system,nano positioning stage.The magnetic beryllium system was used to control the magnetic beads and the feasibility of the magnetic enthalpy system was developed.?2?Exploring the key technology of magnetic tweezer design and manufacturing,including the control of the size of the magnetic tip and the coil making.Analyzing the causes of noise generated by the nanopore,such as Johnson noise,bubble noise,1/f noise and Electromagnetic noise.Doing the research of noise reduction,and improving the signal-to-noise ratio of the obtained via information.According to the needs of the experiment,a three-layer chip with less noise is designed.The thickness of each layer of film is designed according to the stress generated by the film to ensure that the film does not break due to excessive stress.Determine process parameters and deposit a three-layer film structure using LP-CVD,then using photolithography,RIE,wet etching and other techniques to create suspend Si₃N₄.The FIB is etched on the film to obtain nanopores with a diameter of about 25 nm,which lays a foundation for mass production.?3?The magnetic enthalpy system controls the speed of DNA passing through the nanopore to reduce the rate of DNA passing through the nanopore.First,DNA is ligated to biotin-modified primers by PCR,then is purified by phenol-chloroform method to remove enzyme proteins and short-chain DNA.The purity of DNA is detected by UV spectrophotometer,and the content of short-chain DNA is detected by gel electrophoresis experiment to ensure that it can be used in the next experiment.At last the purified DNA is bound to the magnetic beads,e Doing research on the interaction between magnetic beads and nanopores,streptavidin and nanopores,and the detachment time of DNA and magnetic beads at different voltages.The magnetic tweezers were used to manipulate the magnetic bead movement,and the speed of passing the DNA through the nanopore was reduced to 5nm/ms in combination with the nano positioning stage.