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⊥, electrical capacitance, C, coefficient of dynamic viscosity, η, and membrane potential difference δф_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_⊥ and increase of η, while δф_m did not change. The val of E_⊥ 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_⊥ 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 streptavidin considerably stabilized s-BLM by means of the formation of a complex with biotin-modified phospholipids.