Skip to main content
. 2024 Oct 22;18(44):30561–30573. doi: 10.1021/acsnano.4c09017

Figure 3.

Figure 3

Time courses of bubbles and membrane tension. (A) Free running of a CBB. Spontaneous changes were allowed in the system without controlling the bubble pressure. In this scenario, the right bubble (blue) inflated while the left bubble (green) remained nearly constant in volume, with slight increases in the contact angle over time. Consequently, the leaflet tension increased slightly. The time course of the parameters is shown at 10 Hz. (B) 3D Trajectory. This plot shows the contrasting behaviors of the two bubbles. (C) Steady size-clamp. The average radii of the bubbles were maintained with pressure controllers operating frequently, as evidenced by fine and frequent fluctuations in bubble pressures, contact angles, and tensions. (D) Steady tension-clamp. Symmetrical bubble sizes and pressures were set to achieve a bilayer tension of 4 mN·m–1. The membrane tension was clamped for 30 min. During this period, bubble pressure gradually decreased, bubble size expanded, and the contact angle increased slightly. These trends are frequently observed and explained by a gradual increase in lipid density in the monolayers via slow partitioning. Green: left; blue: right; and orange: bilayer. The traces of the left and right leaflets are nearly overlapped. (E) Step tension change and its response under tension-clamp. The bilayer tension was changed stepwise with each simultaneous leaflet tension change of 1 mN·m–1. The feedback control gain (kp and kd) was set to fast for a quick response. The contact angles changed immediately according to the force balance of the monolayers and leaflets. The bubble volume changed gradually at the tension step due to the slow bulk flow of the pipet solution toward the bubble. The inset shows captured images of the bubbles at the tension step (see the video in the Supporting Information). The temporal resolution was 20 Hz. (F) Time course of the tension (leaflets and bilayer) changed on an expanded time scale. The 90% rise time was less than 100 ms (see the video in the Supporting Information). Parameters are shown for the left (blue) and right (green) bubbles.