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Using the electrostriction method we have studied the elasticity modulus perpendicular to the membrane plane, E⊥, and electrical capacitance, C, of supported bilayer lipid membranes (s-BLM), formed on the freshly cut tip of Ag wire, as a function of d.c. voltage applied to the membrane and time. E⊥ was found to change non-monotonically with increasing d.c. voltage U1. These changes depend on the polarity and rate of change of voltage: E⊥ exhibits a strong maximum at around 200–300 mV (aqueous solution positive with respect to the Ag wire, scan rate 100 mV min−1). C decreases almost monotonically but irregularly under these conditions. An increase in the scan rate leads to a shift toward higher voltages of the value at which the marked changes of E⊥ and C take place. Repeated cyclic scans of U1 lead to the stepwise stabilization of E⊥ and C, i.e. the changes of these parameters become less pronounced. Analysis of experimental results suggests that solvent redistribution between support-induced inhomogeneities in s-BLM may be the main cause of the observed effects. |
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