Lipid Bilayer Self-Assembly Simulator

Lipid Mixture

Unsaturated lipids 25%

Temperature 37 °C

Simulation speed 1.0×

Membrane state

Phase

–

Melting point Tm

–

Bilayer thickness

–

Self-assembled

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How it works

Each phospholipid is a coarse-grained bead-spring chain: a polar head bead bonded to two hydrophobic tail beads. Every pair of beads repels at short range (steric exclusion), but tail-tail pairs also attract within a hydrophobic-effect well — while head-head and head-tail pairs stay purely repulsive. That asymmetry alone is enough to drive spontaneous amphiphilic self-assembly: tails cluster together to hide from water, heads spread outward to face it, and a bilayer emerges from disorder.

Unsaturated % — unsaturated tails carry a ~30° kink (cis double bond) that frustrates tight packing, giving pink chains and lowering the mixture's melting point Tm.
Temperature — sets thermal jitter (Langevin noise) on every bead. Below Tm the membrane locks into an ordered gel phase; above Tm it stays fluid (liquid-crystalline), matching how real membrane fluidity depends on both temperature and lipid composition.
Self-assembled % — share of lipids with at least one hydrophobic tail neighbour from another molecule, i.e. incorporated into a bilayer patch.

Head (hydrophilic) Saturated tail Unsaturated tail (kinked) Water

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