Mechanism of Lipid Vesicles Spreading and Bilayer Formation on a Au(111) Surface

Abstract

Spreading of small unilamellar vesicles on solid surfaces is one of the most common ways to obtain supported lipid bilayers. Although the method has been used successfully for many years, the details of this process are still the subject of intense debate. Particularly controversial is the mechanism of bilayer formation on metallic surfaces like gold. In this work, we have employed scanning probe microscopy techniques to evaluate the details of lipid vesicles spreading and formation of the lipid bilayer on a Au(111) surface in a phosphate-buffered saline solution. Nanoscale imaging revealed that the mechanism of this process differs significantly from that usually assumed for hydrophilic surfaces such as mica, glass, and silicon oxide. Formation of the bilayer on gold involves several steps. Initially, the vesicles accumulate on a gold surface and release lipid molecules that adsorb on a Au(111) surface, giving rise to the appearance of highly ordered stripelike domains. The latter serve as a template for the buildup of a hemimicellar film, which contributes to the increased hydrophilicity of the external surface and facilitates further adsorption and rupture of the vesicles. As a result, the bilayer is spread over a hemimicellar film, and then it is followed by slow fusion between coupled layers leading to formation of a single bilayer supported on a gold surface. We believe that the results presented in this work may provide some new insights into the area of research related to supported lipid bilayers.

Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

“…These include scanning probe microscopy, infrared reflective absorption spectroscopy, quartz crystal microbalance, and for conductive supports, electrochemical methods can be used as well [8][9][10][11]. Most popular approaches for supported lipid membrane formation involve vesicles spreading or Langmuir-Blodgett and Langmuir-Schafer techniques [12][13][14][15]. It was demonstrated in numerous research papers that both can produce well-defined planar bilayers with good electrical insulating properties manifested by low differential capacitance and high membrane resistance [7,16].…”

Stimuli-Responsive Extraction and Ambidextrous Redispersion of Zwitterionic Amphiphile-Capped Silver Nanoparticles

“…It was also found that the amount of C16CA ligand on the water-redispersed AgNPs was twice that on the chloroform-redispersed AgNPs (see the Supporting Information). This indicates that a bilayer structure 58,59 was formed on the AgNPs surface. On the other hand, in the methanol solutions, the adsorption was lower and an almost flat isotherm was obtained.…”

Electrochemical Biosensors Based on Membrane-Bound Enzymes in Biomimetic Configurations

“…As a result, a lipid bilayer is formed by rupturing of the vesicles, unrolling, and spreading onto gold substrate. It is assumed that all of these steps depend on the vesicle size [12,13,15,16]. The VF process requires that the initial vesicle radius (R) is higher than the critical adsorption radius (Ra) and lower that the minimum rupture radius (Rr).…”

“…The lipid membrane becomes more fluid and stress within the membrane is released, which is closer to a real biological cell membrane [25]. Atomic force microscopy (AFM) [16], scanning tunneling microscope (STM) [16,26,27], and electrochemical scanning tunneling microscope EC-STM [28] techniques have been employed to obtain molecular imaging information and molecular level resolution about the electrode surface. sBLMs on gold electrodes behave as an ideal capacitor over a large potential range.…”

“…fBLMs are composed by a bilayer that floats ∼2.4 nm over a supporting layer on the surface [21,49] or a monolayer of S-layer protein [50]. The inner leaflet should be a water rich lubricant layer that usually is a water rich polymer [16,[51][52][53] or a hydrogel film [54]. The outer bilayer is deposited by VF [45] or a combination of LB-LS [37,55].…”