Figure 1

The top left image shows schematically the confinement geometry of the DNAs analyzed in this Letter. A phospholipid giant unilamellar vesicle is attached to a substrate by short polymer anchors. The spreading of this attachment region scrapes the end-grafted DNA molecule, stretching and stapling it between the membrane and the substrate as the adhesion front advances. The bottom right image combines in a Janus display (i) a typical optical fluorescence image where the stretched DNAs are seen as bright lines and the coiled DNA regions as bright light spots and (ii) a typical RICM image where the adhesion patch appears as a darker disk. The bottom left and top right drawings further show typical features of the confined geometry.Reuse & Permissions

Figure 2

(a) A typical DNA fluorescence image and (b) a 3D intensity representation of a single DNA cropped from the image. (c) The cross-sectional areas are fit with Gaussian distribution, and the peak of each Gaussian distribution is marked by dark blue star. (d) Intensity profiles of a single DNA image along the longitudinal direction (left) and cross-sectional distribution (right).Reuse & Permissions

Figure 3

(a) Illustration of the conformations of a tapeworm, a DNA chain fully confined below the membrane, and a tadpole, a DNA chain having only a fraction of its length, the tail, confined below the membrane, while the rest of the chain, the head, is in a coiled configuration outside the adhesive patch. (b) Typical profiles of the relative excess length $m(z)$ of tapeworms and tadpoles are shown, respectively, in the left and right insets at ligand fraction $n=1/50$. The average values $\overline{m}$ of the plateau heights are there indicated by arrows, and $z$ is rescaled by the membrane radius $r_c$. The curves in the figure show $⟨m⟩$, an average of $\overline{m}$ values of up to ten chains, as a function of the ligand fraction $n$ for (i) tapeworms (dashed line) and (ii) tadpoles (dot-dashed line). The continuous line shows theoretical predictions for semiflexible chains in a confinement tunnel. [See Eq. (1) and text thereafter.] Clearly, confinement effects alone cannot explain the data, demonstrating the existence of a longer suboptical primitive path for the confining tunnel.Reuse & Permissions