Supported Bilayers Formed from Different Phospholipids on Spherical Silica Substrates

Abstract

Spherical supported bilayer membranes (SS-BLMs) are very attractive candidates in modern bioanalytics and biorecognition studies. A uniform, facile method of preparing different SS-BLMs on silica beads is reported. Confocal fluorescence microscopy and cryo-TEM imaging have been used to characterize these SS-BLMs. Thermal analysis data and FRAP experiments show that the bilayer properties of the SS-BLM are consistent with those of lipid vesicles from which they are formed. The possibility of modulating the size, lipid type and functionality, and mechanical stability makes these rigid liposomes very attractive candidates in biosensors, drug screening, and gene delivery-related applications. This is especially true in work with native vesicle membranes derived from living cells because the existing methods can only accommodate anionic membranes to a limited extent.

Structural basis for the geometry-driven localization of a small protein

“…Previously, we demonstrated that purified SpoVM-GFP selectively bound to lipid vesicles similar in size to the forespore in a mixture of giant unilamellar vesicles of various sizes (24). In the current investigation, we eliminated limitations associated with giant unilamellar vesicles (variability in vesicle size and associated variability in membrane stiffness) by using SSLBs, in which a single phospholipid bilayer is assembled on the surface of silica beads of defined size (29,30). In addition to providing a more strictly defined membrane radius of curvature (determined by the diameter of the silica bead), the use of a supported bilayer system eliminates osmotic-dependent variability in membrane tension across vesicle curvatures (31).…”

“…subtilis strains used in this study are derivatives of PY79 (54). SpoVM-GFPHis 6 or SpoVM P9A -GFP-His 6 purification (24), SSLB preparation (29,30), and microscopy (7) were performed as described previously. All NMR data were acquired at 37°C on Bruker 600-or 850-MHz spectrometers equipped with cryoprobes.…”

Interfacing Zwitterionic Liposomes with Inorganic Nanomaterials: Surface Forces, Membrane Integrity, and Applications

“…13,14 Additional charge or specific chemical interactions have also been harnessed to facilitate SLB formation using a broad range of lipids. 15 The bilayer fluidity, temperature, liposome size and concentration are also found to be important for PC liposome fusion with silica. 8,9 A thin water layer of ~ 1 nm separates the lipid headgroup from the silica surface, 16 allowing the SLB to retain many properties of freestanding membranes.…”

Label-Free Visualization of Ultrastructural Features of Artificial Synapses via Cryo-EM

“…7,13 Importantly, spherical substrates also provide the advantage of accessing different radii of curvature simply by using different size beads. 14 The design of substrates for artificial synapse formation is of great interest both in applied and in fundamental aspects of in vitro studies involving synaptogenesis. However, studies to date have focused mainly on functional similarities between native and artificial synapses and thus often have not pursued the direct visualization of the structural details.…”