AFM and XPS datasets for DNA origami adsorption at single-crystalline TiO2 surfaces

Atomic force microscopy (AFM) images recorded in the dry state of DNA origami triangles adsorbed on TiO2(001), TiO2(110), and TiO2(111) surfaces under different conditions as indicated. Native surface oxided (SiO2) of silicon wafers was used as a control. AFM imaging was performed using a Bruker Dimension Icon operated in ScanAsyst mode with SCANASYST-AIR cantilevers (Bruker). Images were acquired with a scan size of 2 × 2 µm² at a resolution of 1024 × 1024 pixels. X-ray photoelectron spectroscopy (XPS) of the different TiO2 surfaces prior to DNA origami adsorption. XPS measurements were conducted in ultra-high vacuum (base pressure better than 10-10 mbar) using an Omicron ESCA+ system (Omicron NanoTechnology) with a monochromatic Al Kα (1486.7 eV) X-ray source and a hemispherical energy analyzer. The source-analyzer angle was 102°, while the take-off angle of the detected photoelectrons was set to 30° with respect to the surface plane. A pass energy of 100 eV, a step size of 0.5 eV, and a dwell time of 0.1 s were used for survey spectra. A pass energy of 20 eV, a step size of 0.1 eV, and a dwell time of 0.5 s were used for high-resolution core-level spectra. Neutralization was done using simultaneous irradiation with a low energy electron beam (2 eV). Prior to DNA origami adsorption and XPS analysis (dataset "After Cleaning"), the substrates were soaked in Hellmanex III solution (Hellma GmbH) for two hours, rinsed thoroughly with HPLC-grade water (Carl Roth) and subsequently dried under a stream of argon. The cleaned substrates were treated with an O2 plasma (diener Zepto, diener electronic) for 1 minute to create a hydrophilic, hydroxyl-rich surface. For the XPS dataset "After MgCl2", the TiO2 surfaces were additionally incubated for 10 min in 5 mM MgCl2 solution (in water). To avoid any Mg2+ desorption, the surfaces were not washed after incubation but blow-dried in a high-pressure stream of argon.