Continuity of Monolayer-Bilayer Junctions for Localization of Lipid Raft Microdomains in Model Membranes

Abstract

We show that the selective localization of cholesterol-rich domains and associated ganglioside receptors prefer to occur in the monolayer across continuous monolayer-bilayer junctions (MBJs) in supported lipid membranes. For the MBJs, glass substrates were patterned with poly(dimethylsiloxane) (PDMS) oligomers by thermally-assisted contact printing, leaving behind 3 nm-thick PDMS patterns. The hydrophobicity of the transferred PDMS patterns was precisely tuned by the stamping temperature. Lipid monolayers were formed on the PDMS patterned surface while lipid bilayers were on the bare glass surface. Due to the continuity of the lipid membranes over the MBJs, essentially free diffusion of lipids was allowed between the monolayer on the PDMS surface and the upper leaflet of the bilayer on the glass substrate. The preferential localization of sphingomyelin, ganglioside GM1 and cholesterol in the monolayer region enabled to develop raft microdomains through coarsening of nanorafts. Our methodology provides a simple and effective scheme of non-disruptive manipulation of the chemical landscape associated with lipid phase separations, which leads to more sophisticated applications in biosensors and as cell culture substrates.

Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer

“…After that, the prepared vesicle solutions were extruded 20 times through 50-nm-diameter pores (PC membrane, Avanti Polar Lipids Inc., USA) to prepare uniformly sized, small unilamellar vesicles (SUV; 0.1 mg mL −1 ). The 50-nm-diameter SUVs spontaneously rupture on a hydrophilic SiO 2 surface and form a uniform and defect-free SLB patch on the SiO 2 surface of the EG 33 , 34 . For negative controls for biotin–avidin binding, Cholera toxin subunit B proteins (CTxB, Invitrogen, USA, MW= 12 kDa) specifically bound to ganglioside GM1 lipids were used.…”

Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronics transducer

“…After that, the prepared vesicle solutions were extruded 20 times through 50-nm-diameter pores (PC membrane, Avanti Polar Lipids Inc., USA) to prepare uniformly sized, small unilamellar vesicles (SUV; 0.1 mg/mL). The 50-nm-diameter SUVs spontaneously rupture on a hydrophilic SiO 2 surface and form a uniform and defect-free SLB patch on the SiO 2 surface of the EG 42,43 . For negative controls for biotin-avidin binding, Cholera toxin subunit B proteins (CTxB, Invitrogen, USA) speci cally bound to ganglioside GM1 lipids were used.…”

Surface Sensitive Analysis Device using Model Membrane and Challenges for Biosensor-chip

“…Membranes containing SPM, CHOL, and ganglioside GM1 prepared on the S-PDMS regions were found to display a selective accumulation of l o domains at the monolayer regions (Fig. 5c) 20 . Recently, we reported that the heterogeneous SLB patch in different lipid compositions resulted in scheduled l o domain formation, using the methods described in Fig.…”

“…1e). The appropriate surface hydrophobicity (= interfacial energy) for the reconstitution of lipid monolayers in vitro is explained in Ryu et al 20 . In the case of the lipid bilayer, silicabased surfaces (e.g., glass, silicon wafer, and quartz wafer) were piranha cleaned for rendering the hydroxyl (-OH) group on the outermost surface.…”

“…2e). Recently, Ryu et al 20 reported that the inking of dry PDMS into glass surfaces results in the formation of "stamped PDMS (S-PDMS)". These S-PDMSs are ~2-nm-thick and provide hydrophobicity to the lipid monolayer deposition, surrounded by hydrophilic surfaces.…”