Electrostriction of biotin-streptavidin-modified bilayer lipid membranes on a metal support

Using the electrostriction method we have studied the elasticity modulus perpendicular to the membrane plane, E(perpendicular to), electrical capacitance, C, coefficient of dynamic viscosity, eta, and membrane potential difference Delta Phi(m) of supported bilayer lipid membranes (s-BLM) modified by biotin-streptavidin, as a function of d.c. voltage applied to the membrane. Binding of streptavidin to biotin-modified s-BLM resulted in a slight decrease of membrane capacitance, increase of E(perpendicular to) and increase of eta, while Delta Phi(m) did not change. The value of E(perpendicular to) of unmodified membranes was found to change considerably with increasing d.c. voltage and the rate of voltage change. Modification of s-BLM by streptavidin leads to reduced changes of E(perpendicular to) with the rate of d.c. voltage change, and it made s-BLM extremely stable even at an external d.c. voltage of 2 V. Our results indicate that steptavidin considerably stabilized s-BLM by means of the formation of a complex with biotin-modified phospholipids.