a Schematic illustration of the DNA origami, which can polymerize into flat DNA origami sheets due to blunt end stacking. The DNA origami was functionalized with four DNA triplex motifs (red, two are shown), such that its assembly on the GUV membrane is pH-dependent. b Cryo-EM micrographs of the DNA origami plates. The top view (left) and the side view (right) showing the two DNA layers connected at a 90∘ angle. Scale bar: 50 nm. c Schematic illustration of a section of a GUV membrane functionalized with cholesterol-tagged pH-sensitive polymerized DNA origami. At high pH the DNA origami sculpts the GUV membrane. At low pH, it detaches and the GUV relaxes into its spherical shape. (Continued on the following page) d Confocal images of GUVs before (left) and after (right) decreasing the pH from pH 8.3 to pH 5.6 by addition of iso-osmotic potassium dihydrogenphosphate buffer. The GUV (lipids labeled with Atto488, λex = 488 nm) is initially deformed due to the membrane-bound polymerized DNA origami (labeled with Cy3, λex = 561 nm). The DNA origami detaches upon lowering the pH (the fluorescence from the detached DNA origami in the background is too weak to be visible). Scale bars: 10 μm. e Histograms of GUV circularity before (left) and after (right) lowering the pH. At pH 8.3, the mean circularity is 0.94 ± 0.06 (n = 39) compared to 0.991 ± 0.004 (n=20) at pH 5.6, respectively. Source data is available for Fig. 4e.