Supported phospholipid bilayer formation on hydrophilicity-controlled silicon dioxide surfaces

Abstract

We investigated the influence of surface hydroxyl groups (-OHs) on the supported planar phospholipid bilayer (SPB) formation and characteristics. We prepared SiO2 surfaces with different hydrophilicity degree by annealing the SiO2 layer on Si(100) formed by wet chemical treatments. The hydrophilicity reduced with irreversible thermal desorption of -OHs. We formed SPB of dimyristoylphosphatidylcholine on the SiO2 surfaces by incubation at a 100-nm-filtered vesicle suspension. The formation rate was faster on less hydrophilic surfaces. We proposed that a stable hydrogen-bonded water layer on the SiO2 surface worked as a barrier to prevent vesicle adhesion on the surface. Theoretical calculation indicates that water molecules on vicinal surface -OHs take a stable surface-unique geometry, which disappears on an isolated -OH. The surface -OH density, however, affected little the fluidity of once formed SPBs, which was measured by the fluorescence recovery after the photobleaching method. We also describe the area-selective SPB deposition using surface patterning by the focused ion beam.

Formation and fluidity measurement of supported lipid bilayer on polyvinyl chloride membrane

“…The residual trace the photobleached structure is because of the immobile fraction in the SLB. The majority of the SLB on the PVC membrane was continuous, but not perfect, and a part of the SLB existed as isolated SLB patches, or trapped by the 19,28 PVC surface. The size of the isolated SLB patches was submicron, below the resolution of the optical microscope.…”

“…Previous studies by R. Tero et al showed that the SLB of dimyristoylphosphatidylcholine was formed on the thermally treated SiO 2 /Si substrate with WCA of 67°C, but the SLB has small pits and defects. 19,28 Detailed analysis about the microscopic structures of the PVC membrane and the SLB on it is a subject for the future study. Topographic and viscoelastic mapping using atomic force microscope, and high-speed single molecule tracking 30 will provide the valuable information about the structure and dynamics of SLB on the micrometer to submicrometer scales.…”

“…Figure 5 shows the typical example of the FRAP performed in the same condition as Fig.4 for the fluid and continuous DOPC-SLB on a thermally oxidized SiO 2 /Si substrate. 18,19 The lipid molecules diffuse in a lipid bilayer, thus the fluorescence intensity of the photobleached region temporally in a continuous SLB. In case of an adhesive vesicular layer, the photobleached region remains and no recovery proceeds because the vesicles were immobile and isolated from each other.…”

“…A thermally oxidized SiO 2 /Si substrate was also used as a control, because it is a standard sample in our previous studies, [18][19][20][21] where the preparation of vesicle suspensions and SLBs are described in more detail.…”

Effects of Applied Voltage on the Size of Phase-Separated Domains in DMPS-DOPC Lipid Binary Bilayers Supported on SiO₂/Si Substrates

“…Recently, supported lipid bilayers (SLB) are attracting a considerable attention in terms of general interests both as a fluidic membrane supported on a solid surface and as various applications such as biosensors [4]. For realizing biological devices, it is often important to control the spatial patterning of the SLB that has been achieved by various methods, such as using pre-patterned substrates [5], stamping [6], or photo-lithography [7]. However, the patterned structures fabricated by these techniques do not effectively utilize the lateral fluidity of the SLBs.…”