DNA Origami‐Directed Self‐Assembly of Gold Nanospheres for Plasmonic Metasurfaces.

Plasmonic nanostructures are frequently utilized to create metasurfaces with a large variety of optical effects. Control over shape and positioning of the nanostructures is key to the function of such plasmonic metasurfaces. Next to lithographic means, directed self‐assembly is a viable route to create plasmonic structures on surfaces with the necessary precision. Here, a combined approach of DNA origami self‐assembly and electron beam lithography is presented for determinate positioning of gold nanospheres on a SiO2 surface. First, DNA origami structures bind to the electron beam‐patterned substrate and subsequently, gold nanoparticles attach to a defined binding site on the DNA origami structure via DNA hybridization. A sol‐gel reaction is then used to grow a silica layer around the DNA, thereby increasing the stability of the self‐assembled metasurface. A mean yield of 74% of single gold nanospheres is achieved located at the determinate positions with a spatial position accuracy of 9 nm. Gold nanosphere dimers and trimers are achieved with a rate of 65% and 60%, respectively. The applicability of this structuring method is demonstrated by the fabrication of metasurfaces whose optical response can be tuned by the polarization of the incoming and the scattered light. [ABSTRACT FROM AUTHOR]