| DNA(Deoxyribonucleic Acid)contains the genetic information of the whole organism.To get information about DNA sequences fast and accurately can promote the development of life mystery exploration,disease diagnosis,drug development,breeding and other areas.The nanopore device(holes with few of nanometers in diameter)is a promising technology for next-generation DNA sequencing due to its potential to detect label-free single molecule directly with a high throughput at low cost.The well-known principle of nanopore technology,detects fingerprint features in the ion current caused by DNA translocation through nanopore and distinguishes four different types of bases on the DNA strand.Nanopores can be generally divided into two categories according to their materials: biological nanopore and solid-state nanopore.Solid-state nanopore technology has advantages in terms of its outstanding thermal,mechanical,chemical stability and possible large-scale integration.However,the preparation of solid nanopores is limited by complexity,high cost,low yield of the traditional methods.Another problem that constrains the development of solid state nanopore is: the membrane thickness and the DNA fast translocation speed limit the spatial and temporal resolution of the device,which makes the nanopore difficult to reach the single base resolution level.Therefore,how to effectively control the DNA translocation behavior in the nanopore and slow down the DNA translocation speed is of great significance.Here we describe a fast and easily-operated approach for fabricating individual solid-state nanopores with sub-nanometer precision directly on the dielectric membranes by using adjustable pulses controlled dielectric breakdown in electrolyte.Compared with other nanofabrication techniques,the entire fabricating process has been tremendously reduced in complexity and cost and suits for mass production.The pulse parameters are adjustable to suitable for various thickness and material of the membrane.In order to realize the dielectric breakdown process,a custom-designed LabVIEW software controlling a sourcemeter instruments Keithley 2450 was set up to acquire data and measurement automation.Nanopores on graphene and silicon nitride processed by this method both show good stability and perform excellent sensing in DNA sequencing.This project proposes one novel integrated device combining micro-nano nanofiber mesh and nanopore,thus eliminating DNA obstruction of nanopore.Under a certain voltage,the polymer nanofiber mesh unfastens the twining DNA to a linear state,and DNA molecules overcomes the large entropy barrier of nanopores,the translocation speed is slowed down to 136.77 /(7.The physical model of micro-nanometer nanofiber mesh is established by using MATLAB simulation software.The change of ion concentration and electric field distribution near nanopore before and after adding nanofiber are calculated theoretically,finally explains the physical mechanism of nanofiber mesh to affect DNA translocation behavior.In addition,this paper also attempts to prepare nanopore integrated with zinc oxide nanowire,to verify the feasibility for its future application in the field of DNA sequencing.It is gratifying that we firstly obtain the single base signal from graphene nanopore.By increasing the viscosity of the electrolyte in the experiment to slow down the translocation speed of single base through graphene nanopore.The translocation speed of single base is slowed down to the order of milliseconds by using the organic ionic liquid BMIMCl.And try to distinguish different base species.This project will pave the way for developing the next-generation DNA sequencing technology based on nanopore.It will also provide the theoretical supports and basic experimental data for the detection of protein and other long-chain polymers. |
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