Peridynamic Modeling of Ruptures in Biomembranes.
We simulate the formation of spontaneous ruptures in supported phospholipid double bilayer membranes, using peridynamic modeling. Experiments performed on spreading double bilayers typically show two distinct kinds of ruptures, floral and fractal, which form spontaneously in the distal (upper) bilayer at late stages of double bilayer formation on high energy substrates. It is, however, currently unresolved which factors govern the occurrence of either rupture type. Variations in the distance between the two bilayers, and the occurrence of interconnections ("pinning sites") are suspected of contributing to the process. Our new simulations indicate that the pinned regions which form, presumably due to Ca2+ ions serving as bridging agent between the distal and the proximal bilayer, act as nucleation sites for the ruptures. Moreover, assuming that the pinning sites cause a non-zero shear modulus, our simulations also show that they change the rupture mode from floral to fractal. At zero shear modulus the pores appear to be circular, subsequently evolving into floral pores. With increasing shear modulus the pore edges start to branch, favoring fractal morphologies. We conclude that the pinning sites may indirectly determine the rupture morphology by contributing to shear stress in the distal membrane.
Department of Mechanical Engineering, Santa Clara University, Santa Clara, California, United States of America.
Michael
http://orcid.org/0000-0002-3702-4191
M
Taylor
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America.
Irep
http://orcid.org/0000-0002-5379-3273
I
Gözen
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America.
Samir
http://orcid.org/0000-0003-3522-9262
S
Patel
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden.
Aldo
A
Jesorka
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America.
Katia
K
Bertoldi
D000465:Algorithms; D002462:Cell Membrane / Q000737:chemistry*; D017709:Fractals; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D018613:Microscopy, Confocal; D008954:Models, Biological; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D010743:Phospholipids / Q000737:chemistry; D016062:Porosity; D013314:Stress, Mechanical; D013816:Thermodynamics
D008051:Lipid Bilayers; D008563:Membrane Lipids; D010743:Phospholipids