On the formation of a macroscopically flat phospholipid membrane on a hydrosol substrate

Abstract

The dependence of the structure of a phospholipid layer (DSPC and SOPC) adsorbed on a hydrosol substrate on the concentration of NaOH in a solution of 5-nm silica particles has been studied by X-ray reflectrometry with the use of synchrotron radiation. Profiles of the electron density (polarizability) have been reconstructed from the experimental data within a model-independent approach. According to these profiles, the thickness of the lipid film can vary from a monolayer (∼ 35Å) to several bilayers (∼ 450Å). At the volume concentration of NaOH of ∼ 0.5 mol/L, the film on the hydrosol surface is a macroscopically flat phospholipid membrane (bilayer) with a thickness of ∼ 60Å and with areas of 45 ± 2 and 49 ± 3Å 2 per DSPC and SOPC molecule, respectively. * tikhonov@kapitza.ras.ru

Kinetics of the formation of a phospholipid multilayer on a silica sol surface

“…This effect was taken into account by the subtraction of the previously measured average value in this angular range, which was ∼ 0.1 pulses/s. Thus, the data for the reflection coefficient obtained on the diffractometer are comparable in spatial resolution 2π/q max z ≈ 10Å (where q max z ≈ 0.5Å −1 is the maximum value in the experiment) with the data previously obtained with synchrotron radiation [6,7]. Figure 2 shows the experimental dependences of the reflectivity R(q z ) from the surface of clean boundaries of silica sols of (circles, squares) 7-nm and (diamonds, triangles) 12-nm particles.…”

“…We previously observed the crystallization of a multilayer of phospholipid bilayers whose thickness is given by the Debye screening length Λ D in the bulk of a hydrosol substrate on the surface of the aqueous solution of amorphous silicon dioxide nanoparticles [6,7] (Fig. 1).…”

Perspectives for X-ray reflectometry with laboratory sources applied to the analysis of thin films at the surface of multicomponent liquids

“…diffractometer (1) and an ID31 synchrotron station (2). The data are given from [21,22]. Insert: geometry of X-ray scattering from a surface.…”

“…Kinetics of the spontaneous ordering of phospholipid multilayers on the surface of silica sol was discussed in our works [21,22]. We used model lipids 1,2-distearoyl-sn-glycero-3phosphocholine (DSPC) and 1-stearoyl-2-oleoylsn-glycero-3-phosphocholine (SOPC) deposited on the surface of silica sols FM-16 (16% wt.…”

“…The influence of chemical composition of a silica substrate on the structure and properties of the lipid membrane has been also considered in [21]. In particular, the enrichment of SM-30 substrate with alkaline ions (up to 1.3% wt.…”