Study Of Microscopic Manipulation Technology For DNA Molecules

Nano-manipulation is one of the most promising technologies in this century.It performs nano measurement and manufacturing by positioning and control of objects to be manipulated,and has a wide range of applications including almost all the scientific fields such as electronics,material science and biomedicine.In this technology,the atomic force microscope(AFM)has its unique advantage for obtaining three-dimensional(3D)images of samples with high resolution.Much attention has been paid to the technology as it can solve many problems which cannot be solved by other microscopes such as optical and scanning electron microscopes.It has special contributions to nano-biology,including the studies of biological samples on the nano scale and precise manipulation of single biomolecules in culture.In addition,AFMs can also be used to implement the applications in the fields of biomechanics and manipulation by precise control.These will provide accurate information for studying biological macromolecules and the mechanical parameters between molecules.As a typical type of biological macromolecules,DNAs have attracted much attention because it contains genetic information of living things,which is an important research subject in molecular biology.A huge amount of important information such as mechanical information,sequence information and electrical information can be obtained in detail by manipulation of biological macromolecules.Thus,it is of great significance to manipulate DNA molecules by microscopic manipulation technology on the nano scale for the direct exploration of activities of biomolecules,understanding of various important life processes,completion of DNA editing,promotion of the development of next-generation medical technologies,and treatment of various diseases.In this thesis,the state of the art of nanomanipulation technology was first analyzed.The significance of the work,microscopic imaging of DNA molecules based on AFM manipulation,principle of manipulation system,system configuration,imaging modes,and applications were introduced.High resolution imaging methods for DNA molecules were studied in both air and liquid environments using modification methods with different solutions on mica surfaces.The control of DNA distributions was implemented by electric field,and the corresponding mechanical model was established.Finally,the manipulation,stretching and cutting of DNA molecules were achieved.The stretches of DNA molecules were controlled by electric field,the cutting was realized by mechanical force and enzymatic cleavage on nano scale.This work will form a solid base for future accurate positional sequencing,editing of DNA molecules and the development of nano materials and devices.