DNA Origami-templated Construction Of Metal Nano-patterns And Its Surface Plasmonic Properties

The bottom-up organization of noble-metal nanoparticles (NPs) withnanometer-scale precision is an important goal in nanotechnology. Owing to theirunique surface-plasmon resonances,well-defind metal namoparticle arrys could beused to develop applications in nanophotonics and nanoelectronics. Enormousprogress has been made in the DNA guided organization of nanoparticles intodiscrete, one dimensional, two-dimensional and three-dimensional architectures.DNA nanotechnology is a vehicle for the controllable assembly of nanoparticles8because it enables the positioning of particles with nanoscale precision and thetailoring of their binding interactions. DNA origami, which is based on the folding along single-stranded DNA scaffold with the help of hundreds of short complementarystaple strands, can create almost any arbitrary2D even3D shapes.Every stable strandis unique on the DNA origami,which make it nano-addressable and a perfecttemplate for metal nanoparticles self-assembly.Here we constructed a variety of Metal nanopatterns using thenano-addressablity of DNA origami.1. First, we built a variety of shapes of superorigami using the simpletwo-dimensional DNA origami through the hybridization of the sticky ends. weadjusted the number of sticky ends projecting from the DNA origami, and getsuperorigami with high yield, which is prepared for the assembly of metalnanopatterns on DNA origami next step. We improved the yield of hexamer DNAorigami structures formed from the triangles effectively. Using the same design, wehave synthesized the triangular DNA origami dimer and trimer.2. The nano-addressablity of DNA origami made the self-assembly of metalnanoparticles (NPs) with nanometer-scale precision easily. We designed a strategy to organize gold nanopaticles that uses the hybirdization of sticky-ends projecting fromthe DNA origami with the DNA modified on gold nanoparticles. The positions of thepaticles and spacings between them were controlled by the positions of thesticky-ends. The plamonic coupling between the gold nanoparticles depend on thegeomitry of the nanostructures,the shap and size of the particles and the spacingbetween them. Especially with small particles, optical measurements on individualnanostructures become extremely difficult due to their smallscattering cross sections.We construted gold naoparticles clusters from the small one and got the5nm goldnaoparticle heptermaers on DNA origami with high yield.Then we extended to thebig gold nanoparticles whose diameters ranged from30nm to80nm. We constructeddimer,trimer and hexamer of these big gold nanoparticles.3. Sububwavelength metallic structures enable the broad manipulation ofelectromagnetic fields at the nanoscalebecause of their ability to support surfaceplasmons, which are oscillations of free electrons in metal that couple with theelectromagnetic field. We constructed80nm gold nanoparticle dimer, trimer,tetramer and50nm-80nm gold nanoparticle dimer. We realized the Dark-fieldmicroscopy and scanning electron microscopy colocalization theough the marker onthe conductive glass. With this method, we got the scattering spectru of these goldnanoparticle clusters and discover the Fano-like resonance on the asymmetric80nmgold nanoparticle tetramer.4. Herein we used a conceptually new, simple and straightforward in situmetallization method which utilizes artificial defects in DNA origami structure asnucleation and growth positions to achieve the large-scale site-specific copperplating with nano-resolution.We successfully constructed a variety of parttens, suchas "seven dots","digetal8"and "digital88", on the DNA origami through the selectivecpooer metallization.