Applications Of DNA Origami In Chiral Plasmonic Materials And Nanomedicine

1953, Waston and Click proposed a spiral model, double helix, for the molecular structure of DNA. This discovery is the start of glorious days for the molecular biochemistry. DNA is widely known as genetic materials and regarded as the symbol of biotechnology. However, professor Seeman believed DNA molecules can be used as bricks to construct two-dimension and three-dimension lattice. Over the thirty years, scientist have developed many methods to design and assembly a multitude of DNA nanostructures, which own many unique features that other materials do not. DNA nanotechnology shows huge potentials in many fields, such as self-assembly materials, DNA computing, drug delivery and diagnosis. DNA nanotechnology is becoming one of the most promising areas.Plasmon-induced circular dichroism is a very interesting phenomenon. Theoretical calculations show that helix assemblies of gold nanoparticles have optical activity. However, preparation of chiral plasmonic nanostructures needs to control the positions of gold nanoparticles precisely. DNA nanostructures show huge potential in organizing nanoparticles. Gold nanoparticles, silver nanoparticles, quantum dots, carbon nanotube and proteins are well assembled on the DNA origami. So self-assembly based on DNA nanostructures is one of the best choices for construction chiral metal nanostructures.With a high level of structural programmability and obvious biocompatibility, self-assembled DNA nanostructures are among the most promising candidates to serve as nanoscale carriers for drug delivery. The potential of DNA origami structures for nanomedical applications has gained great interest. Intensive study is needed to fully understand the interactions between DNA nanostructures and cells, the cell uptake process, intracellular behavior of DNA nanostructures.The main contents are as follows: 1. Various kinds of DNA nanostructures and assemblies of nanoparticles based on DNA origami are reviewed. Then the concept of plasmon induced circular dichroism was introduced. Finally, this thesis expounds the necessity to explore the biological effects of DNA materials.2. The rectangular DNA origami is selected as template to assembly gold nanoparticles. Two parallel chains of gold spheres are constructed. After that, the rectangle DNA nanostructures curl into tubes after the addition of "folding strands". Gold nanoparticles on DNA template formed helix nanostructures. The morphology of helix assemblies was characterized by TEM. Steady signal of optical activity were obtained.3. A convenient label-free fluorescent strategy is developed to probe the distribution and stability of DNA origami in live, cellular systems. An intriguing carbazole-based biscyanine molecule with the effects of aggregation induced emission is used as a fluorescent probe.