Fig. 6: Rings formed from DNA nanotubes contract upon addition of a molecular crowder or heating.
From: Triggered contraction of self-assembled micron-scale DNA nanotube rings
a Confocal images of uncontracted (left) and contracted (right) DNA nanotube rings formed from 50 nM DNA tiles, 500 nM starPEG-(KA7)4 in 1x PBS and 10 mM MgCl2 without and with 25 wt% 500 kDa dextran. Scale bar: 2 μm. b DNA nanotube ring diameter after 15 min heating to 35 and 40 °C, respectively (Mean ± SD, n = (31, 30, 30) DNA nantube rings analyzed per condition). Mann-Whitney test with p-values from left to right: ****≤0.0001, *0.0106. c DNA nanotube ring diameter for different molecular weights of 25 wt% dextran (2'500, 35'000, 70'000, 250'000, 500'000 g/mol) (Mean ± SD, n = (32, 32, 31, 32, 31, 30) DNA nanotube rings analyzed per condition). Mann–Whitney test with p-values from left to right: ****≤0.0001, *0.0221, *0.0434, ns 0.5787. d Experimental DNA nanotube ring diameter reduction by depletion attraction as a function of molecular weight of dextran at 25 wt% (black, identical to data points in c, constant total number of dextran monomers). Depletion theory (turquoise, see text and Supplementary Note 3) assumes a penetrable layer of crosslinkers (thickness p) around DNA nanotubes (thickness d0). Parameters fitted to experimental ring diameters (black, see c (Mean ± SD, n = (32, 32, 31, 32, 31, 30) DNA nanotube rings analyzed per condition)): DNA nanotube diameter d0 = 18.6 ± 2.4 nm, penetration depth p = 11.0 ± 3.3 nm, attraction strength due to crosslinkers εcross/kBT = 0.31 ± 0.14. Source data are provided as a Source Data file.
