Sculpting 2D Crystals via Membrane Contractions before and during Solidification.

Area of Science:

• Biophysics
• Materials Science
• Soft Matter Physics

Background:

• Giant unilamellar vesicles (GUVs) are model systems for cell membranes.
• Phospholipid crystallization within GUVs leads to 2D solid formation.
• Crystal morphology in GUVs is complex and varies with conditions.

Purpose of the Study:

• To investigate the morphology evolution of phospholipid crystals in GUVs.
• To understand the mechanisms driving different crystal shapes.
• To map experimental observations to theoretical models.

Main Methods:

• Experimental observation of phospholipid crystallization in GUVs.
• Analysis of crystal growth and morphology.
• Surface Evolver computations to model membrane tension and morphology.
• Identification of key physical parameters influencing crystal formation.

Main Results:

• Crystals exhibit size-dependent morphology in moderate lipid concentrations.
• High lipid concentrations lead to compact crystals or flower-like structures.
• Flower petal formation is favored at high membrane tension to minimize bending energy.
• Stress relaxation via water permeation follows an R^2 scaling.

Conclusions:

• Phospholipid crystal morphology in GUVs is governed by a balance of bending, line, and tension energies.
• Vesicle size and lipid concentration are critical factors in determining crystal shape.
• Computational models successfully predict observed crystal morphologies, highlighting the importance of processing parameters.