Dr. Tim Liedl of the University of Munich will be presenting a seminar entitled Tailoring Light with DNA Self-Assembled Nanostructures.

Abstract: DNA self-assembly and in particular DNA origami is an emerging technology that allows the construction of arbitrarily shaped nanoscale objects exhibiting multiple functionalities. In DNA origami, a long single-strand DNA "scaffold" is folded into shape with the help of hundreds of synthetic oligonucleotides, so-called "staple" strands. The resulting DNA nanostructures can be designed to adopt any three-dimensional shape and can be addressed through DNA-hybridization or chemical modification with nanometer-precision. I will introduce applications of this robust assembly method, such as the design of pre-stressed "tensegrity" nanostructures  (tensegrity is a fusion word of "tension" and "integrity" and is used as a building principle in art and architecture), the formation of hybrid DNA origami nanopores for single-molecule detection, the construction of molecular carrier systems and the fabrication of self-assembled nanoscopic material with designed optical properties. Complex assemblies of nanoparticles – including magnetic, fluorescent and plasmonic nanoparticles – have been realized and will be presented. We achieved spatial control over particle placement better than 2 nm and attachment yields of 97% and above. By assembling chiral particle helices, strong optical activity in the visible range can be generated. As a collective optical response emerging from such objects dispersed in solution, we detected pronounced circular dichroism (CD) originating from the plasmon-plasmon interactions in the particle helices. In very recent experiments, we were able to show that the orientation of the helices in respect to the incoming light beam critically influences the resulting CD spectra. Our results can be explained with theoretical models based on plasmonic dipole interaction and demonstrate the potential of DNA origami for the assembly of plasmonic metafluids with optical properties defined by design.

Faculty host: Dr. Jason DeRouchey