Membrane-Potential-Induced Electroporation as a Physical Mechanism for Metal Nanoparticle Penetration through a Cell Membrane

A mechanism of the penetration of nanosized metal particles from an ambient solution into the cytoplasm of a living cell, has been proposed. The driving force of this new mechanism is membrane potential, i.e., the potential difference between the cellular cytoplasm and the ambient solution. The essence of the mechanism consists in the fact that a metal particle occurring at a cell membrane shunts the potential drop in the diffuse part of the electrical double layer of the membrane. As a result, almost the entire membrane potential, which, at a normal state of the cell, is distributed between its electrical double layer and the lipid bilayer of the cell membrane, appears to be completely applied to the latter. As a consequence, the field strength in the lipid bilayer rises, thereby increasing the probability of the formation of a pore in it, through which a metal particle with a diameter lying in a certain range (in the case under consideration, from two to three tens of nanometers) can penetrate into the cytoplasm without inflicting any damage on the cell.