Influence of phospholipid molecular structures on cell membrane mechanical response under tension

What is it about?

Biological cell membranes are primarily comprised of a diverse lipid bilayer with multiple phospholipid (lipid) types, each of which is comprised of a hydrophilic headgroup and two hydrophobic hydrocarbon tails. The lipid type determines the molecular structure of head and tail groups, which can affect membrane mechanics at nanoscale and subsequently cell viability under mechanical loading. Hence, using molecular dynamics simulations, the current study investigated seven membrane phospholipids and the effect of their structural differences on physical deformation, mechanoporation damage, and mechanical failure of the membranes under tension. The obtained results suggest that larger headgroup structure, greater degree of unsaturation, and tail-length asymmetry influenced the phospholipids' ability to pack against each other, increased the fluidity and equilibrium area per lipid of the membrane, and resulted in lower failure strain. Overall, this study provides insights on how different phospholipid structures affect membrane physical responses at the molecular level and serves as a reference for future studies of more complex membrane systems with intricate biophysical properties.

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Photo by Landon Arnold on Unsplash

Photo by Landon Arnold on Unsplash

Why is it important?

In this paper, we investigate the effects of diverse chemical structures of lipid molecules on the physical dynamics of the biological cell membrane at molecular scale. Experimental observations have shown that the interactions between different chemical structures of headgroup, acyl chain lengths, and saturations of lipids affect the membrane biophysical properties and mechanical behaviors. However, there are variations in the reported values, the contribution of each structural feature remains unclear, and the molecular details of membrane nanomechanics are still elusive. Hence, implementing atomistic molecular dynamics (MD) simulations, the current study examined seven membrane phospholipids and their structural variation underpinning membrane molecular properties and physical response. The study offers new insights into experimental studies on the impacts of lipid molecules on biophysics of membrane systems at nanoscale, and contributes to future research on chemical physics of more various molecular assemblies with complex biochemical-biophysical properties.