Characterizing Stability Properties of Supported Bilayer Membranes on Nanoglassified Substrates Using Surface Plasmon Resonance

Abstract

Supported bilayer membranes (SBMs) formed on solid substrates, in particular glass, provide an ideal cell mimicking model system that has been found to be highly useful for biosensing applications. Although the stability of the membrane structures is known to determine the applicability, the subject has not been extensively investigated, largely because of the lack of convenient methods to monitor changes of membrane properties on glass in real time. This work reports the evaluation of the stability properties of a series of SBMs against chemical and air damage by use of surface plasmon resonance spectroscopy and nanoglassified gold substrates. Seven SBMs composed of phosphatidylcholine and DOPC+, including single-component, mixed, protein-reinforced SBMs (rSBMs) and protein-tethered bilayer membranes (ptBLMs), are studied. The stability properties under various conditions, especially the effects of surfactants, organic solvents, and dehydration damage on the bilayers, are compared. PC membranes are found to be easily removed from the glassy surfaces using relatively low concentrations of the surfactants, while DOPC+ is markedly more stable toward nonionic surfactant. DOPC+ membranes also demonstrated remarkable air stability while PC films exhibited considerable damage from dehydration. Doping of cholesterol does not improve PC's stability against SDS and Triton but changes the lipid membrane packing enough to protect against dehydration damage. Although rSBMs and ptBLMs improve air stability to a certain degree, they are still quite susceptible to significant damage/removal from ionic and nonionic surfactants at lower concentrations. Overall, DOPC+ has noted higher stability on glass, likely due to the favorable electrostatic interaction between the silicate surface and the lipid headgroup, making it a good candidate for application. Nanoglassy SPR proves to be an attractive platform capable of rapidly screening film stability in real-time, providing critical information for future work using supported membranes for sensing applications.

Interaction of poly(ethylene glycol)-conjugated phospholipids with supported lipid membranes and their influence on protein adsorption

“…We also performed FRAP experiments for the supported lipid bilayer membrane, which was formed by a vesicle fusion on a hydrophilic glass surface (Figure 2(B) (part b)). [27,28] The lateral diffusion coefficient of the bilayer membrane on the glass was calculated to be 1.55 × 10 −8 cm 2  s –1 and was similar to that obtained for the monolayer membrane. This result indicates that the supported lipid monolayer membrane has almost the same property as the supported bilayer membrane and is acceptable as a model surface.…”

PEGylated Phospholipid Membrane on Polymer Cushion and Its Interaction with Cholesterol

“…The fatty acyl chain of the phospholipids is flexible and is able to complement perfectly the shape of cholesterol such that the number of hydrophobic contacts is high and the packing is tight. 32,33 The amount of cholesterol may vary with the type of membrane; too high level of cholesterol will cause cells to be too rigid and further the blood pressure problems, whereas decreased amounts of sterol in the membrane increase glucose and ions permeability. 34,35 It has been reported that cholesterol incorporated into phospholipid membrane has a dynamic effect as its molar fraction changes: 36 10-30 mol % cholesterol mixed lipid layer has densely packed and ordered structures, but the 50 mol % cholesterol induces membrane structures irregular and disordered.…”

Mix and Match: Coassembly of Amphiphilic Dendrimers and Phospholipids Creates Robust, Modular, and Controllable Interfaces

“…The stability of these lipid bilayer structures upon introduction of a chemical perturbant was investigated using established SPR methods. 33 After vesicle fusion and rinsing of the membrane under PBS flowing at 5 mL/h, 0.1% (v/v) surfactant was introduced to the SPR flow cell at a rate of 20 mL/h, and buffer was rinsed through at this rate for 5 min. Upon return of the flow rate to 5 mL/h for 10 min, relative membrane removal was quantified through percent change of the minimum resonance angle as shown below, where Δ θ 0 represents the angular shift after vesicle fusion and Δ θ f represents the final angular shift after surfactant rinsing.…”