Several Applications Of DNA Self-assembled Structures

DNA has been demonstrated as an ideal material for nanoscale self-assemblybecause of its specific secondary structure, sequence programmability and accurateself-recognition, etc. The concept of employing DNA as material leads to the emergingarea of DNA nanotechnology. In past thirty years, great efforts were made to buildnearly arbitrary static nanostructures and various dynamic structures. With thedevelopments of DNA self-assembly, exploring the potential applications of DNAself-assembled structures is becoming the core issue and hotspot of this area. Thisdissertation aims to explore the application of DNA self-assembled structures in twoareas: DNA nanomachine regulated bivalency and DNA self-assembled structuredirected amphiphilic self-assembly.In the first part, we designed a DNA machine that can reversibly regulate targetbinding affinity on the basis of distance-dependent bivalent binding. It is a tweezer-likeDNA machine that can tune the spatial distance between two ligands to construct ordestroy the bivalent binding. The DNA machine can strongly bind to the target proteinwhen the ligands are placed at an appropriate distance but releases the target when thebivalent binding is disrupted by enlargement of the distance between the ligands. This“capture release” cycle could be repeatedly driven by single-stranded DNA withoutchanging the ligands and target protein.In the second part, we studied the DNA self-assembled structure directedamphiphilic self-assembly. We designed an amphiphilic molecular with a ssDNA as itshydrophilic part, which associates the DNA self-assembly and amphiphilicself-assembly by DNA hybridization. First we studied the co-assembly of DNA and theamphiphilic molecular under thermodynamic controlled annealing process, the resultsshowed that these two kinds of self-assembly occurred simultaneously and correlatively.In the annealing process, a local high concentration area formed by DNA self-assemblyand its hybridization with the amphiphilic molecules, then the area induced the freeamphiphilic molecules assembled in this area, which conversely influenced theself-assembly of DNA. Based on these results, we next prepared an amphiphilicself-assembled layer structure with defined size using DNA assembled structure as atemplate. A two-dimensional DNA origami structure with ssDNA overhangs on one of its surfaces was pre-formed and purified, then using the same local high concentrationstrategy, the DNA origami first hybridize the amphiphilic molecules and then directedits self-assembly on its surface. The amphiphilic self-assembly formed a layer structurewith similar size and shape with the layout of overhangs on the DNA origami. Finally itformed a DNA origami supported and water soluble nanoscale amphiphilic layerstructure with defined size and shape.