Exploration Of Metal-ion-free Buffer And Design Of New Tiles For DNA Self-assembly

DNA is a kind of bio-macromolecule with genetic information,which is also an excellent programmable building block.Nadrian C.Seeman supposed that DNA supramolecule could be utilized for the fabrication of highly ordered structures in the 1980s.Over the past three decades,there have been three main strategies developed for DNA self-assembly:DNA tile-based assembly,DNA origami and single-strand tiles(SST)assembly.DNA self-assembly,not only greatly enriches the diversity and complexity of nano/micro-structures,but also exihibits great potential in the fields ranging from sensing,guided assembly,and biomedicine.We mainly carry out the research on two aspects as following:1.We developed a "metal-ion-free" buffer based on ethylenediamine(EN)for DNA self-assembly.In a typical experiment,the DNA strands are mixed in a magnesium-containing aqueous buffer,followed by a slow thermal annealing process.However,magnesium(or other metal cations)is not desired in some cases,for example,metal cations may influence the impact of metal-dependent enzymes on DNA nanostructures.In order to eliminate the limitations,we develop a kind of"metal-ion-free" buffer based on ethylenediamine for DNA self-assembly.The details are as follows:(1)Two-dimensional array and three-dimensional nanocage of tetrahedron are successfully obtained in the EN buffer based on DNA double-crossover tile and 3-arm tile,respectively.(2)Exploring the application of EN buffer in biology system.Our result shows that the activity of DNase I is restrained in new buffer due to the absence of magnesium ion.(3)Builing up a general pH regulation system.We can reversibly control the assembly and disassembly of DNA tetrahedron by changing the pH value of buffer owing to the pH-sensitive property of EN molecule,which provides a sequence-independent pH-responsive strategy.2.The parallel crossover 4-arm DNA tile is designed and utilized for assembly of DNA tubular nanostructure.Previous DNA tiles are mostly based on antiparallel crossover.In order to increase the diversity of DNA tiles and nanoassemblies,we design a new 4-arm tile based on parallel crossover,which has been used for the successful assembly of one-dimensional DNA tubular nanostructure.