Fabrication Of Three-Dimensional Nano-Structures Controlled By DNA Bonds

It is well known that the basic structural units of geometric configurationand small differences in spatial morphology have great impact on the results of the bottom-up assembly.Therefore,it is particularly important to develop a method which can assemble basic structural units of different geometric configurations into highly ordered two-dimensional and three-dimensional structures through simple preliminary design,and effectively control the interaction between these basic structural units.DNA,a molecule with convenient ability as well as effective binding ability with nanoparticles,can design and manufacture the target material at nano-meterscale This unique compilation capability is based on the Watson-Click interaction,so it is entirely programmable and predictable.However,DNA is a kind of biological macromolecule which is soft and sensitive to the surrounding environment.As a result,DNA structure will suffer serious damage when encountered with harsh external environment(high temperature,high salt,strong acid and strong base,etc),resulted in undesirabled assembly structures and functionaliyies.Scientists have investigated the advantage of DNA nanotechnology during the assamble process,but the stability of DNA-guided nano structures has not been well explored,in different physical and chemical environments,which limits the further application of these micro-and nano-scaled materials.In this paper,the assembly of large-scale DNA structures and the construction of DNA-guided nanoparticle superlattices were successfully fabricatedby making full use of the complementary pairing principle of DNA bases and the effective control of thermodynamic and dynamic processes in the assembly process,as well as integrity and orderliness of DNA assembly under different assembly environments are also studied.1.It was critical for the efficient use of DNA structure,to explore the relationship between the order of superlattice fabricated by DNA guided gold nanoparticles and environmental factors(such as salt concentration,pH,base number,temperature,etc).Moreover,we used DNA to guide the assembly of gold nanoparticles to construct the ordered superlattice structure of body centered cube,and explored its stability under different physical and chemical environments by changing different external environmental factors and using small-angle X-ray scattering(SAXS)technology to characterize.The results showd that though DNA was a relatively weak and sensitive biological macromolecule,it was resistant to the external environment when we used DNA to guide the self-assembly of gold nanoparticles to fabricate the superlattice structure.2.Ithas been wide concern to construct pH-responsive DNA origami structures and further explore its application in biosensing and other aspects by scientistsHowever,most of the existing reports relied on special DNA sequences with acid-base triggering systems.If this acid-base triggering system can be separated from the DNA sequence,it will greatly reduce the design difficulty of the DNA structure and improve the application scope of this dynamic structure.In this paper,we used a pH-responsive buffer for non-metallic ions to replace the original buffer and explore the assembly mode of rectangular and octahedral origami structuresin different environments.3.The physical and chemical properties of close-in assembly meet the needs of many cutting-edge technologies.In this paper,based on the DNA nanotechnology,we designed a three-dimensional DNA nanostructure that self-assembled by special methods,and made the gold nanoparticles overcome strong spatial and electrostatic repulsion,achieving seamless contact between gold nanoparticles and DNA nanostructures andfabrictainga stable self-assembly structure.This method provides a possibility for design of new materialswith new property.