DNA Origami Adsorption and Lattice Formation on Different SiO_x Surfaces

Self-assembled DNA origami lattices on silicon oxide surfaces have great potential to serve as masks in molecular lithography. However, silicon oxide surfaces come in many different forms and the type and history of the silicon oxide has a large effect on its physicochemical surface properties. Therefore, we here investigate DNA origami lattice formation on differently fabricated SiO_x films on silicon wafers after wet-chemical oxidation by RCA1. Despite having similar oxide compositions and hydroxylation states, of all surfaces tested, only thermally grown SiO_x performs similarly well as native oxide. For the other SiO_x films deposited by plasma-enhanced chemical vapor deposition and magnetron sputtering, DNA origami adsorption is strongly suppressed. This is attributed to an increased surface roughness and a lower oxide density, respectively. Our results demonstrate that the employed SiO_x surface may decide over the outcome of an experiment and should be considered as an additional parameter that may require optimization and fine-tuning before high-quality lattices can be assembled. In particular, our observations suggest that efficient DNA origami lattice assembly on SiO_x surfaces requires a low surface roughness and a high oxide density.