Influence of phase separating lipids on supported lipid bilayer formation at SiO₂surfaces

Abstract

The importance of the lipid phase on the formation of supported lipid bilayers (SLBs) via vesicle fusion and on the resulting SLB homogeneity at SiO(2) surfaces has been studied by the quartz crystal microbalance with dissipation (QCM-D) monitoring technique. Physiologically relevant lipid compositions were chosen to correspond to different regions (l(d), l(o) and coexistence of phases) in established phase diagrams of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), N-palmitoyl-D-erythro-sphingosylphosphorylcholine (PSM) and cholesterol. For most compositions, SLBs formed through vesicle rupture in a critical-surface-coverage dependent manner. Inclusion of PSM and cholesterol into POPC vesicles significantly impaired the vesicle rupture process such that a higher critical concentration of vesicles on the surface was needed before the rupture process started. When increasing the cholesterol content the vesicles formed SLBs containing more defects in the form of intact vesicles adsorbed on the surface up to a point (l(o) phase) where vesicles did not break at all but formed supported vesicular layers. The hampering of vesicle rupture is interpreted in terms of the ability of cholesterol to accommodate vesicle deformation. Experiments using elevated temperatures to alter the lipid membrane into a more fluid phase significantly improved the quality of the SLB showing the importance of both cholesterol content and the lipid phase on SLB homogeneity.

Antimicrobial Mechanism of Monocaprylate

“…5A). The formation of SLB occurred in a similar manner as previously reported for other lipid compositions (40). The resulting membrane gave a resonance frequency shift of Ϫ27.1 Ϯ 0.9 Hz and a concomitant dissipation change of (0.44 Ϯ 0.5) ϫ 10 Ϫ6 (Fig.…”

“…The QCM profile during the SLB formation differed from E. coli SLB by containing a second phase of adsorption before rinsing with MOPS. Such a phase has previously been linked to adsorption of intact vesicles onto the membrane surface for complex lipid compositions (40). The process showed a significant baseline drift of frequency and dissipation over time (0 to 15 min, Fig.…”

Deuterium-labelled N-acyl-l-homoserine lactones (AHLs)—inter-kingdom signalling molecules—synthesis, structural studies, and interactions with model lipid membranes

“…Supported lipid bilayers were produced via the method of vesicle fusion [62]. Appropriate amounts of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (POPG) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were dissolved in chloroform (Avanti Polar Lipids Inc.) in a glass vial to obtain a final lipid concentration of 2.5 mg/mL.…”

Preserved Transmembrane Protein Mobility in Polymer-Supported Lipid Bilayers Derived from Cell Membranes

“…high cholesterol content/lipid diversity [14][15][16][17] or high protein density 17,18 ). Several strategies to induce vesicle-substrate fusion of such systems have been investigated 19 , including α-helical (AH) peptide-induced fusion 14 , bilayer edge-induced fusion 16,17 , and synthetic/native membrane vesicle co-adsorption 11,12 .…”