Overview of DNA curtain assay. (A) Lipid bilayers formed around streptavidin passivate the surface of a microfluidic flow cell. Applying flow leads to DNA stretching while streptavidin remains still. (B) In a DNA curtain assay, a lipid-bound DNA migrates in the same direction as the buffer flow direction until it is stopped by a diffusion barrier. (C) The top view of flow-stretched singly-tethered DNA molecules shown in (B). (D) A double-tethered DNA in a DNA curtain assay. One end of the biotinylated DNA is tethered to streptavidin and the other digoxigenin-tagged DNA end binds to an anti-digoxigenin antibody on a pedestal. (E) DNA curtain assay with single-stranded (ss) DNA produced by a rolling circle replication. For efficient ssDNA stretching, fluorescently labeled replication protein A (RPA) can be introduced. All figures in Figure 2: not drawn to scale.
