Probing Membrane Viscosity and Interleaflet Friction of Supported Lipid Bilayers by Tracking Electrostatically Adsorbed, Nano‐Sized Vesicles. Issue 46 (30th September 2016)

• Record Type: Journal Article
• Authors: Tabaei, Seyed R.; Gillissen, Jurriaan J. J.; Cho, Nam‐Joon
• Is Part Of: Small. Volume 12:Issue 46(2016)
• Page Start: 6338
• Page End: 6344
• Publication Date: 2016-09-30
• Subjects: inter‐leaflet friction -- lipid vesicles -- membrane viscosity -- single particle tracking -- supported lipid bilayers; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201601561
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract : Particle tracking is used to measure the diffusional motion of nanosized (≈100 nm), lipid vesicles that are electrostatically adsorbed onto a solid supported lipid bilayer. It is found that the motion of membrane‐adhering vesicles is Brownian and depends inversely on the vesicle size, but is insensitive to the vesicle surface charge. The measured diffusivity agrees well with the Evans–Sackmann model for the diffusion of inclusions in supported, fluidic membranes. The agreement implies that the vesicle motion is coupled to that of a nanoscopic lipid cluster in the upper leaflet, which slides over the lower leaflet. The diffusivity of membrane‐adhering vesicles is therefore predominantly governed by the interleaflet friction coefficient, while the diffusivity of single lipids is mainly governed by the membrane viscosity. Combined with fluorescence recovery after photobleaching analysis, the interleaflet friction coefficient and the membrane viscosity are determined by applying the Evans–Sackmann model to the measured diffusivity of membrane adhering vesicles and that of supported membrane lipids. This approach provides an alternative to existing methods for measuring the interleaflet friction coefficient and the membrane viscosity. Abstract : The viscosity and the interleaflet friction coefficient of lipid bilayers are measured by tracking the diffusional motion of individual nano‐sized lipid vesicles that are electrostatically targeted onto a supported lipid bilayer (SLB). The vesicle motion is coupled to that of a nanoscopic lipid cluster in the upper leaflet and induces slippage between the upper and the lower leaflets of the SLB.