Fig. 4

Melittin-induced membrane disruption and vesicular cargo release. a Melittin association to the supported lipid bilayer (SLB) and melittin-induced disruption of the membrane for increasing melittin concentrations (1, 10, and 100 µM). The time evolution of the melittin linear regression signal (purple) shows melittin-membrane association and partial dissociation phases for each melittin injection time step. The increase in melittin signal is accompanied by a clear decrease in the lipid regression signal (blue) evidencing loss-of-membrane integrity, which intensifies with increasing melittin concentrations. b Sketch of the vesicle cargo release experiment. The sensor metasurface is functionalized with hydrophilic tethers displaying cholesterol moieties, which are then used to capture lipid vesicles loaded with the neurotransmitter gamma-aminobutyric acid (GABA). Injection of melittin perforates the lipid vesicle membrane, resulting in a release of GABA cargo molecules. c Time-resolved linear regression signals for the three characteristic biological components in the experiment: lipid, GABA, and melittin. After the injection of GABA-loaded vesicles, successful attachment of intact, loaded vesicles to the surface is corroborated by the stable lipid and GABA regression signals. The strong initial peak of the GABA signal is caused by the transient flow of extravesicular GABA molecules present in the bulk solution. Melittin injection results in a fast and pronounced decrease of the GABA signal, indicating efficient cargo release