Elasticity and mechanical instability of charged lipid bilayers in ionic solutions

• Published in: The European physical journal. E, Soft matter and biological physics Vol. 37; no. 8; p. 26
• Main Authors: Avital, Yotam Y., Grønbech-Jensen, Niels, Farago, Oded
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2014; EDP Sciences
• Subjects: Biological and Medical Physics; Biophysics; Chemistry; Colloidal state and disperse state; Complex Fluids and Microfluidics; Complex Systems; Elasticity; Exact sciences and technology; General and physical chemistry; Ions - chemistry; Lipid Bilayers - chemistry; Membranes; Nanotechnology; Physics; Physics and Astronomy; Polymer Sciences; Regular Article; Soft and Granular Matter; Solutions - chemistry; Static Electricity; Surfaces and Interfaces; Thin Films; Living systems: Biological Matter; Monte Carlo method; Ionic solution; Elasticity; Lipids; Bilayer; Coulomb interaction; Mechanism; Charge density; Simulation; Bending; Instability; Counter ion; Membrane; Membrane pore; Elastic properties
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2014-14069-2

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We use coarse-grained Monte Carlo simulations to study the elastic properties of charged membranes in solutions of monovalent and pentavalent counterions. The simulation results of the two cases reveal trends opposite to each other. The bending rigidity and projected area increase with the membrane charge density for monovalent counterions, while they decrease for the pentavalent ions. These observations can be related to the counterion screening of the lipid charges. While the monovalent counterions only weakly screen the Coulomb interactions, which implies a repulsive Coulomb system, the multivalent counterions condense on the membrane and, through spatial charge correlations, make the effective interactions due to the charged lipids attractive. The differences in the elastic properties of the charged membranes in monovalent and multivalent counterion solutions are reflected in the mechanisms leading to their mechanical instability at high charge densities. In the former case, the membranes develop pores to relieve the electrostatic tensile stresses, while in the latter case, the membrane exhibits large wavelength bending instability.
Graphical abstract