Surface potential-dependent assembly of DNA origami lattices at SiO2 surfaces†

Abstract

Self-assembled DNA origami lattices have promising applications in the fabrication of functional surfaces for sensing and plasmonics via molecular lithography. While surface-assisted DNA origami lattice assembly at mica surfaces is a straightforward and widely employed method, technologically more relevant SiO₂ surfaces still pose a challenge. Lattice assembly on SiO₂ surfaces is very sensitive toward environmental conditions and surface properties, which often results in comparably low lattice order even under optimized conditions. Here, we investigate DNA origami lattice assembly at oxidized silicon wafers at room temperature with an applied negative substrate potential. In situ atomic force microscopy reveals that lattice assembly is notably affected by the applied potential, with −120 mV resulting in the highest lattice order after 120 min incubation. The obtained degree of order, however, is lower than that of lattices assembled under equivalent potential-free conditions at an elevated substrate temperature. Varying the concentrations of monovalent and divalent ions in the electrolyte only leads to a further decrease in lattice order. While our results demonstrate the important role of the surface potential in surface-assisted DNA origami lattice assembly, they also suggest that the achievable degree of lattice order is limited by additional factors such as the roughness of the SiO₂ surfaces.