Fluid Biomembranes Supported on Nanoporous Aerogel/Xerogel Substrates

Abstract

Planar supported lipid bilayers have attracted immense interest for their properties as model cell membranes and for potential applications in biosensors and lab-on-a-chip devices. We report the formation of fluid planar biomembranes on hydrophilic silica aerogels and xerogels. Scanning electron microscopy results showed the presence of interconnected silica beads of approximately 10-25 nm in diameter and nanoscale open pores of comparable size for the aerogel and grain size of approximately 36-104 nm with approximately 9-24 nm diameter pores for the xerogel. When the aerogel/xerogel was prehydrated and then allowed to incubate in l-alpha-phosphatidylcholine (egg yolk PC) unilamellar vesicle (approximately 30 nm diameter) solution, lipid bilayers were formed due to the favorable interaction of vesicles with the hydroxyl-abundant silica surface. Lateral mobility of labeled lipid N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine was retained in the membranes. A diffusion coefficient of 0.61 +/- 0.22 microm(2)/s was determined from fluorescence recovery after photobleaching analysis for membranes on aerogels, compared to 2.46 +/- 0.35 microm(2)/s on flat glass. Quartz crystal microbalance-dissipation was utilized to monitor the kinetics of the irreversible adsorption and fusion of vesicles into bilayers on xerogel thin films.

Nanoporous Microbead Supported Bilayers: Stability, Physical Characterization, and Incorporation of Functional Transmembrane Proteins

“…1 Since this discovery, a great deal of research interest has focused on the development of biomimetic supported bilayer systems incorporating various polymeric, ceramic, and functionalized substrates [2][3][4][5][6][7][8][9][10][11] for the introduction of membrane proteins for bio-and chemical sensing, drug discovery and delivery, and fundamental biophysical studies in near-native environments.…”

Planar bilayer lipid membranes supported on mesoporous aerogels, xerogels, and Vycor® glass: an epifluorescence microscopy study

“…This information can be acquired by quartz crystal microbalance-dissipation, which is a powerful tool in quantitatively resolving lipid configurations on surfaces [35]. Our QCM-D results indicated slower kinetics for vesicle adsorption and transformation into bilayers on the mesoporous surfaces compared to glass [36]. A larger amount of mass in the final lipid assemblies on xerogels was also indicated by the QCM-D results, which suggested a combination of supported lipid bilayers and some unfused vesicles on the surface.…”

ITO/Poly(Aniline)/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers

“…They show that the lipid films are laterally continuous, and are not composed predominately of adsorbed vesicles (for which the percent recovery would be minimal) [38]. The percent recovery shows that about 10% of the bilayer is immobile on the timescale of the measurement, which is attributable to the greater surface roughness of the sol-gel surface relative to glass (on which the recovery is typically close to 100%) [28, 39, 40]. …”