Combined topographic and fluorescence scans of DNA origami nanosctructures. DNA origami consists of many pieces of single stranded DNA that fold into an interlinked double helix structure (a). Two pieces of DNA are modified with the fluorescent dye Atto655 (yellow dots in (a)). Because of their unique position in the DNA nanostructure due to base pairing, they appear at the same position for every DNA triangle. The bottom side of the structure (blue line) is 120 nm long. The fluorescence intensity and the AFM topography are shown in (b) and (c), respectively. The position of the nanostructure is determined from the AFM image (d) and transferred to the fluorescence image (e) to confirm the position of the dyes with respect to the triangle geometry. (f) shows a section through the center of the dark spots from which their distance can be determined. The scale bar is the same for all panels.