Piezoelectricity of phospholipids: A possible mechanism for mechano-, and magneto-receptions in biology

Antal Jákli ,John Harden ,Cody Notz ,Chris Bailey
Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent, Ohio 44242 USA
Classically, the phospholipid bilayer within the cell membrane has been considered as a flexible and self-healing barrier between the inside and outside of the cell, as well as a structural unit to support functional proteins. Here we show that the phospholipids may not play just a passive role, but may act as active transducers. By periodically shearing and compressing films of hydrated L-alpha-Phosphatidylcholine, we induced tilt of the molecules with respect to the bilayer’s normal and produced electric current perpendicular to the tilt plane. This effect occurs due to SmA* liquid crystal phase structure of the bilayers, which under molecular tilt becomes a ferroelectric SmC* phase where the polarization is normal to the tilt plane. We find that a 5 degree tilt yields a polarization of 300 nC/cm2. We suggest that this coupling allows for a wide variety of sensory possibilities of cell membranes such as mechano-reception. We also hypothesize that rotation of magnetic particles found in migratory animals can induce local reorientation of the lipid molecules, which via this piezoelectric effect can produce electric signals that may trigger firing of nerve cells, thus allowing navigation based on magnetic information. We demonstrate this hypothesis by generating electric currents in hydrated phospholipids doped with 0.5wt% of ferrofluid of magnetite (Fe3O4) nanoparticles when less than a 100G alternating magnetic field.

Full Document