Fig. 2: Membrane wetting by PEG/dextran and glycinin condensates.
From: Wetting and complex remodeling of membranes by biomolecular condensates
a Confocal microscopy images showing partial out-wetting of a vesicle (red) by a dextran-rich droplet (green) in phase-separated PEG/dextran aqueous two-phase systems; the vesicle adopts a moon-like shape. b Partial wetting leads to the formation of a contact line between the \({ce}\) interface (blue line) and the membrane. The contact line partitions the membrane into the \({ie}\) (magenta) and \({ic}\) (purple) segments, with the contact angles \({\theta }_{c}\) + \({\theta }_{i}\) + \({\theta }_{e}\) = 360°. c Force balance between the droplet interfacial tension \({\Sigma }_{{ce}}\) and the mechanical tensions \({\Sigma }_{{ie}}^{m}\) and \({\Sigma }_{{ic}}^{m}\) within the two membrane segments. These three tensions form the sides of a triangle (which implies Eqs. 9 and 10 in “Methods”)52. d Experimental data for the geometric factor \(\Phi=\left({{\sin }}{\theta }_{e}-{{\sin }}{\theta }_{c}\right)/{{\sin }}{\theta }_{i}\) (Eqs. (8)–(11) in “Methods”) as a function of NaCl concentration. The largest possible value \(\Phi\) = + 1 (red circle) corresponds to the transition from dewetting to partial wetting at [NaCl]≈43 mM, the smallest possible value \(\Phi\) = −1 (blue circle) reflects the transition from partial wetting to complete wetting at [NaCl]≈180 mM. All data: mean ± SD, n = 10 per composition. Data for the geometric factor of the PEG/Dextran system can be found in Supplementary Fig. 1b. The inset shows the phase diagram of glycinin in salt solutions with the region of phase coexistence shown in cyan. The locations of the measured geometric factor data points are indicated with stars. e Examples of confocal microscopy images of different wetting morphologies for the data points indicated in (d); for more images see Supplementary Fig. 1a. All scale bars: 10 µm. Data for panel d are provided as a Source Data file.
