Fig. 2

Isotherms and structures of the natural and synthetic PSurf. a Surface pressure-surface area isotherms of natural PSurf containing 0 and 20 mol% of VEA. Here, isotherms of synthetic PSurf with/without 20 mol% VEA are presented for comparison. b1–b3 Wide-field images of natural PSurf containing 0, 20, and 40 mol% of VEA collected at three representative surface pressures. c Surface pressure isotherms of synthetic PSurf vs. average area per lipid (APL) containing 0 to 40 mol% of VEA. The region indicating a change in phase behavior is highlighted (dashed line). d1–d3 Wide-field images of synthetic PSurf with 0, 20, and 40 mol% VEA collected at three representative surface pressures. The inset in d2 (middle) represents a magnification (× 4) with better brightness and contrast. Scale bar is 50 μm.