Formation of Supported Membranes from Vesicles

Abstract

Using a combination of the quartz crystal microbalance and surface plasmon resonance techniques, we have studied the spontaneous formation of supported lipid bilayers from small (approximately 25 nm) unilamellar vesicles. Together these experimental methods measure the amount of lipid adsorbed on the surface and the amount of water trapped by the lipid. With this approach, we have, for the first time, been able to observe in detail the progression from the adsorption of intact vesicles to rupture and bilayer formation. Monte Carlo simulations reproduce the data.

Protein Adsorption on Supported Phospholipid Bilayers

“…Furthermore we can in the QCM-D system directly from the shape and quantitative values of the f and D shifts judge the quality of the SPB preparation. This is not the case with the SPR curve, which contains less information (29). To put our results into the context of earlier measurements on protein-resistant surfaces we compare them in Table 2 with ellipsometry results reported by Malmsten (5), for spin-coated PC (third row in Table 2), and for PC triple layers on hydrophobic surfaces made by Langmuir-Blodgett deposition (5) (fourth row in Table 2).…”

“…2. At t = 0 s, the pure SiO 2 surface is exposed to the vesicle solution, resulting in a rapid and large decrease in frequency, f (mass uptake due to vesicle adsorption), and increase in energy dissipation, D. A minimum in f and a maximum in D are reached at ∼40 s, which is (approximately) the coverage at which adsorbed intact vesicles start to fuse and transform into a bilayer (23,29,30). Before the maximum/minimum, f increases due to the mass load of the adsorbed, intact vesicles, and D increases due to the high internal energy dissipation in the soft vesicles, subject to the oscillatory shear motion of the sensor surface.…”

“…Simultaneously the adlayer becomes more rigid, and consequently the dissipation goes down. This part of the experiment has already been reported and subjected to a detailed analysis (23,29,30). In this work we investigate the protein adsorption properties of the SPB formed in this way.…”

The Role of Surface Free Energy on the Formation of Hybrid Bilayer Membranes

“…Nevertheless, the process occurs very rapidly under ambient conditions. Using the quartz crystal microbalance technique, Keller et al 48 showed that a major difference between phospholipid monolayer addition on a hydrophobic surface and phospholipid bilayer addition on a hydrophilic surface is that in the former case, no adsorption of vesicles to the surface can be discerned.…”

“…For hydrophilic surfaces, vesicle adsorption, rupture, and addition of a lipid bilayer are well known and have been extensively studied by Seifer and Lipowsky 19, [41][42][43][44] and recently by Kasemo and Zhdanov. [45][46][47] In general, the driving force for vesicle rupture and fusion at a hydrophilic surface is the surface adhesion energy. 18,19 The strong interaction between the surface and an adsorbed vesicle leads to vesicle deformation stress, pore formation, and, finally, to fusion between vesicles and addition of a bilayer to the hydrophilic surface.…”