The Self-Assembly Of DNA Macromolecule Based On Rolling Circle Amplification

In 1953,Watson and Click introduced the double helix configuration of DNA that opened the door to molecular biology.Then DNA nanotechnology was developed.The self-assembly of DNA is considered as a good way to build DNA nanostructures in recent decades,based on the specific programmability and recognizability of DNA molecules.This method includes DNA origami,DNA module assembly,etc.However,due to the complexity of sequence design and the limitation of nano-scale expansion,the development of this method is limited to some extent.In order to simplify the tedious sequence design and further extend the size range of DNA nanostructures,we have developed a simple and effective method for building large-scale DNA assembly.In this paper,DNA nanostructures with different widths and sizes were prepared based on long single strand DNA synthesized by Rolling circle amplification(RCA),and they were characterized by transmission electron microscopy(TEM)and atomic force microscope(AFM),etc.On the other hand,a DNA hydrogel was prepared by hyper branched rolling circle amplification(HRCA).The morphology of the gel was not only characterized,the rheological properties of the gel were also studied.The main research contents of this paper include the following aspects:(1)For the realization of rolling circle amplification,we design the template cyclization scheme,and used polyacrylamide gel electrophoresis to characterization and purification the product.On the other hand,we explore the influence of the different shear enzyme added for on the synthetic product,and the synthesis product was characterized by ultraviolet spectrum.The product was proved to be the preset cyclic DNA product by the rolling circle amplification experiment.We also discussed the influence of on the experimental RCA andHRCA products,using agarose gel electrophoresis,transmission electron microscope,scanning electron microscopy to characterize the products.This research established the foundation for the preparation of long chain DNA used in the construction of nano-assemblies.(2)We constructed nanoscale ladders using the long chain DNA macromolecule synthesized by RCA and the short chain DNA.By changing the length and number of the short chain,and remaining sticky end in a single nanometer on one or both sides,the ladder is clever successfully self-assemblied as thi-nanoladder,penta-nanoladder,and nanobracade.The nanoscale ladders were characterized by transmission electron microscopy and atomic force microscope,which showed the width and uniform nanometer ladder with correspond width was obtained,and the concept of design was proved.(3)We used HRCA technology to prepare a DNA physical hydrogel,which was observed with three-dimensional network structure by the transmission electron microscope and scanning electron microscope.The rheological properties of hydrogel are discussed preliminarily,the effects of angular frequency,strain and temperature on the viscoelasticity of gel were investigated,and the main forces which include the formation of could form gels were analyzed briefly.