Thermal membrane fluctuations determine the uptake of a trapped particle into giant unilamellar vesicles

Particle uptake is of huge interest in pharmacology and medicine, but a user-controlled uptake of particles into GUVs has been technically demanding. Here, we indent the membrane of differently composed GUVs with optically trapped particles until particle uptake. By continuous 1MHz back-focal-plane interferometric tracking and autocorrelating the particle’s positions within 30µs delays for different indentations, the fluctuations’ amplitude, the damping, the mean forces, and the energy profiles were obtained. The study demonstrates that soft matter can interact completely differently on different temporal and spatial frequency modes, which are excited by the environmental thermal noise.