Atomic Force Microscopy Observation Of The Deposition And Extending Of DNA Molecules On Several Kinds Of Substrate Surfaces

Nano-technology is based on the modem advanced technology. It is a product integrated the modern science, which includes the chaos physics, quanta physics, meso-physics, molecular biology, and the modern technology, which includes computer technology, microelectronic technology, scanning tunnel microscope technology, nucleo-analysis technology together. The meaning of nano-science exists in the all around nature and biosphere. Actually, the nano-science and technology and the molecule machine have existed long before. If the animal and plants are defined by the tiniest benchmark, they are the combinations integrated by these nano-machines. The most well-known in these nano-machines are the protein, ribonucleic acid (RNA), and enzyme, which can assist the cell with regenesis and restoring.DNA is an attractive candidate for the study in nanoscale positioning of biological molecules because of its exquisite specificity in base pairing, ~1 nm radius combined with large aspect ratio, and ready availability. It has attracted attention as a device material in the field of nanobioelectronics on the basis of its characteristics such as self-assembly, electric conductivity and the capacity to interact with various chemicals and biomaterials. Direct physical mapping of DNA and DNA-protein complexes with atomic force microscopy (AFM) has been an attractive topic in recent years for the nanometer spatial resolution and the variety of acceptable environmental conditions (vacuum, air, liquid) afforded by AFM. Since the invention of the AFM , imaging of DNA has been one of the most eagerly anticipated applications. AFM imaging of uncoated DNA molecules has great potential for contributing to a detailed knowledge of the substructure of individual DNA molecule and the understanding of processes involving DNA. In this thesis, the deposition and extending of double-strand DNA on several kinds of surfaces were observed by AFM.The deposition and extending of double-strand DNA on three kinds of surfaces using the flowing of liquid were successfully observed by AFM. And the molecule of DNA can be disconnected by supersonic machine.On the basis of APS, a new modification material was synthesized. By comparing AFM imagines on two kinds of substrates that respectively treated withAPS and newly synthesized modified material, it was found the latter have more clean background. Furthermore, the structures of DNA molecules varying with concentration of new modification agent were studied, and it was found that when the new modification agent concentration (volume ratio) was 1:1000, DNA molecules were successfully fixed and extended on the modified mica surface and well-distinguished DNA strands were imaged by AFM.