Fluidic-based “DNA curtain”. (A) Schematic design of DNA alignment along a diffusion barrier by hydrodynamic flow. (B) Immobilization of the free ends of the aligned DNA molecules on anchors forms a DNA rack, where DNAs remained stretched in the absence of flow. This setup has been used to elucidate the searching modes (e.g., 3D collision or 1D sliding) of the DNA repair complex (purple) for a DNA damage site (red star). (C) Scheme of single-molecule replication by the E. coli replisome on a circular DNA template aligned along a barrier etched by a diamond-tip scribe. The growing DNA curtain is stained by Yo-Pro1, a DNA intercalating fluorescent dye, as the templates are extended. Images are reproduced from Ref. 58, 60, and 61.