Properties of a Self-Assembled Phospholipid Membrane Supported on Lipobeads

Abstract

The overall objective of our work was to make a hydrogel-supported phospholipid bilayer that models a cytoskeleton-supported cell membrane and provides a platform for studying membrane biology. Previously, we demonstrated that a pre-Lipobead, consisting of phospholipids covalently attached to the surface of a hydrogel, could give rise to a Lipobead when incubated with liposomes because the attached phospholipids promote self-assembly of a phospholipid membrane on the pre-Lipobead. We now report the properties of that Lipobead membrane. The lateral diffusion coefficient of fluorescently labeled phosphatidylcholine analogs in the membrane was measured by fluorescence recovery after photobleaching and was found to decrease as the surface anchor density and hydrogel crosslinking density increased. Results from the quenching of phosphatidylcholine analogs suggest that the phospholipid membrane of the Lipobead was composed mostly of a semipermeable lipid bilayer. However, the diffusional barrier properties of the Lipobead membrane were demonstrated by the entrapment of 1.5-3.0 K dextran molecules in the hydrogel core after liposome fusion. This hydrogel-supported bilayer membrane preparation shows promise as a new platform for studying membrane biology and for high throughput drug screening.

Lipogels: Single-Lipid-Bilayer-Enclosed Hydrogel Spheres

“…In many SPBs, however, slower lateral diffusion is typically observed. 58 In our Lipogels, the lipid bilayer coating may well not be smooth but rather may be corrugated because of imperfections in, and the finite thickness of, the shell region, which produces, in turn, a nonplanar distribution of hydrophobic anchor positions. Such corrugations would yield a slower apparent lateral diffusion coefficient overall.…”

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.…”

Characterization of radioligand binding to a transmembrane receptor reconstituted into Lipobeads

“…1A). More recently, we have confirmed that the Lipobead membrane is composed mostly of two leaflets of phospholipid and has the ability to encapsulate large hydrophilic solutes [8]. In the present study, we were interested in determining whether transmembrane receptors could be incorporated onto the surface of these Lipobeads and retain native function.…”