Over the last decade, the DNA origami technique has consolidated into the state-of-the-art approach for the self-assembly of nanophotonic structures since it provides unique control and versatility to organize different molecules and nanoparticles in well-defined geometric arrangements. In particular, this technique has proven extremely useful to fabricate nanophotonic devices with specific functionality by setting single-photon emitters, such as fluorescent molecules or quantum dots, and metallic nanoparticles in precise geometries with high positional and stoichiometric control.
In this contribution, we will first introduce this technique and discuss its strengths and limitations together with a comparison with state-of-the-art top-down approaches. Then we will show how this technique can be applied to study light-matter interaction at the single molecule level for enhanced spectroscopies and how these antennas can be engineered to manipulate the fluorescence emission, including directivity, and emission spectrum.
In addition, we will discuss our recent results on the development of a technique to functionalize high-index dielectric colloidal Si NPs with DNA sequences using click-chemistry. To further demonstrate these findings, we self-assemble Si NP dimers using the DNA origami technique. Furthermore, we also exploit the DNA origami technique to position both Si NPs and organic fluorophores at controlled gaps to study the distance dependance energy transfer, the modification on the fluorescence rates and the emission directivity. Our results show that in the vicinity of the Si NPs the radiate rate increases more than the non-radiative rate and that the Kerker condition can be exploited to obtain emission unidirectionality.
Finally, we focused on manipulating the orientation of single dyes on DNA origami in order to control the coupling with optical antennas. In particular, we exploit the ability of DNA origami to exert forces in order to “stretch” covalently incorporated dyes and deterministically align them with the orientation of double-stranded DNA helix they are located at.