We measured the conductance of bilayer lipid membranes of diphytanoylphosphatidylcholine induced by interaction with cubic magnetic nanoparticles (MNPs) of cobalt ferrite 12 and 27 nm in size and coated with a hydrophilic shell. The MNP coating is human serum albumin (HSA) or polyethylene glycol (PEG). The interaction of nanoparticles added to the bulk solution with the lipid bilayer causes the formation of metastable conductive pores, which, in turn, increases the integral conductance of the membranes. The increase in conductance with increasing MNP concentration was practically independent of the particle size. The dependence of the bilayer conductance on the concentration of PEG-coated MNPs was much weaker than that on the concentration with a shell of HSA. Analyzing the current traces, we believe that the conductive pores formed as a result of the interaction of nanoparticles with the membrane can change their size, remaining metastable. The form of multilevel current traces allows us to assume that there are several metastable pore states close in energy. The average radius of the putative cylindrical pores is in the range of 0.4–1.3 nm.

The electrical conductivity of azolectine bilayer lipid membranes is observed to increase 10–40-fold with respect to its background value of 67 ± 13 pS/mm² upon the addition of cubic CoFe₂O₄ nanoparticles with the main diagonal of 14 nm (MNP-14) and 27 nm (MNP-27). As the concentration of MNP-14 in the membrane solution increases from 50 to 450 µg/mL, the increase in the membrane conductivity with respect to its background value is nonlinear and can be approximated by the exponential dependence with exponent 2.75. Discrete current pulses are observed in the constant voltage mode for the MNP-14 concentration higher than 250 µg/mL and for all MNP-27 concentrations starting from 50 µg/mL, which points to the appearance of conducting lipid pores.