Abstract

We use the DNA origami method for the fabrication of functional self-assembled nanoscopic objects and materials. By offering attachment sites for active nano-components on these DNA objects, we have realized complex and nanometer-precise assemblies of fluorophores and plasmonic nanoparticles.

We are exploring molecular interactions with plasmonic nanoantennas made by DNA origami. The nanoantennae are built up by pairs of gold nanoparticles on DNA origami templates at separation distances between 9 nm and 3 nm in order to achieve strong plasmonic coupling and thus the formation of plasmonic ‘hot spots’. The constructs can be used as efficient probes for surface enhanced Raman spectroscopy (SERS) and as platforms for studying excitonic interactions with plasmon resonances. By combining the plasmonic hot spots with molecular excitons, plexitonic states can be attained and varying the size of the nanoparticles allows us to reliably tune the plasmon resonance of our nanoantennae to match the absorbance frequency of the exciton.

In recent experiments we studied force interactions between biomolecules by employing a DNA origami force spectroscopy device without any physical connection to a micrometer-sized bead or cantilever. We exploit the entropic elasticity of single-stranded DNA to apply tension on two biomolecular systems mounted on our device: the transition behavior of a Holliday junction and the bending of a DNA promotor sequence induced by the TATA -binding protein (TBP). We are able to generate reliable single-molecule force spectroscopy data in the piconewton range in a high throughput fashion. Our DNA origami force spectrometer can in principle be employed with a wide variety of DNA interacting biomolecules.