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In vitro membrane model systems are used to dissect complex biological phenomena under controlled unadulterated conditions. In this context, lipid monolayers are a powerful tool to particularly study the influence of lipid packing on the behavior of membrane proteins. Here, monolayers deposited in miniaturized fixed area-chambers, which require only minute amounts of protein, were used and shown to faithfully reproduce the characteristics of Langmuir monolayers. This assay is ideally suited to be combined with single-molecule sensitive fluorescence correlation spectroscopy (FCS) to characterize diffusion dynamics. Our results confirm the influence of lipid packing on lipid mobility and validate the use of FCS as an alternative to conventional surface pressure measurements for characterizing the monolayer. Furthermore, we demonstrate the effect of lipid density on the diffusional behavior of membrane-bound components. We exploit the sensitivity of FCS to characterize protein interactions with the lipid monolayer in a regime in which the monolayer physical properties are not altered. To demonstrate the potential of our approach, we analyzed the diffusion behavior of objects of different nature, ranging from a small peptide to a large DNA-based nanostructure. Moreover, in this work we quantify the surface viscosity of lipid monolayers. We present a detailed strategy for the conduction of point FCS experiments on lipid monolayers, which is the first step toward extensive studies of protein-monolayer interactions., (Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Model membrane systems have become invaluable tools to investigate specific features of cellular membranes. Although a variety of different experimental assays does exist, many of them are rather complicated in their preparation and difficult in their practical realisation. Here, we propose a new simple miniaturised monolayer assay that can easily be combined with standard analytical techniques such as confocal fluorescence microscopy and fluorescence correlation spectroscopy (FCS)., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Self‐organizing patterns of purified Min proteins, which are spatial regulators of bacterial cell division, and the cell division protein FtsZ were observed when the proteins were reconstituted in emulsion droplets, as reported by P. Schwille and co‐workers in their Communication on page 13455 ff. The cover illustrates FtsZ filament bundles (blue) and Min proteins (red) in the lumen of a droplet, with a lipid monolayer (green) at the droplet interface (image by G. Chwastek). [ABSTRACT FROM AUTHOR]