When lipid membranes curve or are subjected to strong shear forces, the two apposed leaflets of the bilayer slide past each other. The drag that one leaflet creates on the other is quantified by the coefficient of interleaflet friction, b. Existing measurements of this coefficient range over several orders of magnitude, so we used a recently developed microfluidic technique to measure it systematically in supported lipid membranes. Fluid shear stress was used to force the top leaflet of a supported membrane to slide over the stationary lower leaflet. Here, we show that this technique yields a reproducible measurement of the friction coefficient and is sensitive enough to detect differences in friction between membranes made from saturated and unsaturated lipids. Adding cholesterol to saturated and unsaturated membranes increased interleaflet friction significantly. We also discovered that fluid shear stress can reversibly induce gel phase in supported lipid bilayers that are close to the gel-transition temperature.

当脂质膜弯曲或受到强剪切力时，双层的两个并置的小叶会彼此滑过。一个小叶对另一小叶产生的阻力通过小叶间摩擦系数b来量化。该系数的现有测量范围超过几个数量级，因此我们使用最近开发的微流体技术在支持的脂质膜中系统地测量它。使用流体剪切应力迫使支撑膜的顶部小叶在静止的下部小叶上滑动。在这里，我们表明该技术可以对摩擦系数进行可重复的测量，并且足够灵敏，可以检测饱和和不饱和脂质制成的膜之间的摩擦差异。在饱和和不饱和膜中添加胆固醇显着增加了叶间摩擦力。我们还发现，流体剪切应力可以可逆地在接近凝胶转变温度的支撑脂质双层中诱导凝胶相。