Electric field-driven transformations of a supported model biological membrane--an electrochemical and neutron reflectivity study.
نویسندگان
چکیده
A mixed bilayer of cholesterol and dimyristoylphosphatidylcholine has been formed on a gold-coated block of quartz by fusion of small unilamellar vesicles. The formation of this bilayer lipid membrane on a conductive surface allowed us to study the influence of the support's surface charge on the structure and hydration of the bilayer lipid membrane. We have employed electrochemical measurements and the specular reflection of neutrons to measure the thickness and water content in the bilayer lipid membrane as a function of the charge on the support's surface. When the surface charge density is close to zero, the lipid vesicles fuse directly on the surface to form a bilayer with a small number of defects and hence small water content. When the support's surface is negatively charged the film swells and incorporates water. When the charge density is more negative than -8 micro C cm(-2), the bilayer starts to detach from the metal surface. However, it remains in a close proximity to the metal electrode, being suspended on a thin cushion of the electrolyte. The field-driven transformations of the bilayer lead to significant changes in the film thicknesses. At charge densities more negative than -20 micro C cm(-2), the bilayer is approximately 37 A thick and this number is comparable to the thickness determined for hydrated multilayers of dimyristoylphosphatidylcholine from x-ray diffraction experiments. The thickness of the bilayer decreases at smaller charge densities to become equal to approximately 26 A at zero charge. This result indicates that the tilt of the acyl chains with respect to the bilayer normal changes from approximately 35 degrees to 59 degrees by moving from high negative charges (and potentials) to zero charge on the metal.
منابع مشابه
Fluctuations and destabilization of single phospholipid bilayers.
Supported phospholipid bilayers are interesting model systems for biologists and present fascinating physical properties. The authors present an extensive experimental study of the dynamic properties of supported bilayers. The structure and the equilibrium properties of single and double supported bilayers were investigated with neutron reflectivity. The submicronic fluctuation spectrum of a ne...
متن کاملNeutron reflection from interfaces with biological and biomimetic materials
During the past decade, neutron reflectivity has increasingly become an important technique for the characterization of biological and biomimetic thin films. Advancements in instrumentation, sample environment and measurement protocols now make it possible to obtain Angstrom-level information about the composition of these materials along the axis perpendicular to the plane of the membrane. A n...
متن کاملInfluence of Membrane Sealing in Pressure-Driven Test Cells on Their Performance
This communication demonstrates the relevance of membrane sealing in a test cell to its performance. Membranes need to be sealed, and therefore a more or less signifcant (depending on the test cell design) peripheral part of the membrane is supported directly by the cell body (instead of a permeate spacer). Although it may seem that there should be no fltration through ...
متن کاملEffective zero-thickness model for a conductive membrane driven by an electric field.
The behavior of a conductive membrane in a static (dc) electric field is investigated theoretically. An effective zero-thickness model is constructed based on a Robin-type boundary condition for the electric potential at the membrane, originally developed for electrochemical systems. Within such a framework, corrections to the elastic moduli of the membrane are obtained, which arise from charge...
متن کاملElectrochemical Properties and Antibacterial Activity of Polyvinyl Chloride Supported Silver Molybdate Ion-Exchange Composite Membrane
Polyvinyl chloride supported silver molybdate composite material is used to develop by solution casting method. This membrane was characterized by various instrumental techniques such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) analyses. These characterizations are used to understand the functional groups,thermal sta...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Biophysical journal
دوره 86 3 شماره
صفحات -
تاریخ انتشار 2004