Changes in Electrical Properties of Bilayer Lipid Membranes Induced by Colloidal Magnetite (Fe3O4) Nanoparticles in a Static Inhomogeneous Magnetic Field

The changes of electrical parameters of azolectin membranes in a static inhomogeneous magnetic field at the one-sided addition of positively charged quasi-spherical superparamagnetic magnetite nanoparticles (MNPs) with a diameter of about 4 nm were studied. The magnet was located at different distances from the membrane, and nanoparticles were attracted to the membrane surface with different strengths by the magnetic field. After the addition of MNPs, a decrease in capacitance, polarization, and further depolarization of the membranes was observed. Zero current appeared on the bilayer lipid membranes (BLMs). There was no unambiguous dependence of the zero current on the membrane depolarization and there were no dependences of the zero current on the strength of the magnetic field and on the concentration of added MNPs. The membrane conductivity increased on average with an increase in the external magnetic field and depended on the ionic strength. Magnetic field caused a rapid accumulation of MNPs on the surface of the BLMs. As a result, the membrane was polarized. Depolarization of the membranes occurred when MNPs passed through the BLMs. The increase in conductivity reflected the processes of lipid bilayer disordering.