Interface dynamics of lipid membrane spreading on solid surfaces

As a model system for two-dimensional interface dynamics. we study the wett ing front of a lipid membrane moving over a solid substrate that is structu red with regularly spaced pinning centers. By analyzing the contour of the front, we derive the normal growth rate and the relaxation coefficient. Bot h exhibit a 1/t(1/2) time dependence. Moreover, the friction coefficient an d the line tension can be determined. Randomly distributed pinning centers cause a fractal contour line. whereas on surfaces: that are artificially ro ughened, self-affine contour lines are observed. The latter exhibit an anom alous roughness exponent of zeta = 0.81 +/- 0.05.