Figure 1.

(a) Surface pressure, (reduction in surface tension compared to a clean water interface with a surface tension of 72 mN/m) vs trough area cyclic isotherms of 800 µg lipid bilayer dispersion deposited on a buffered subphase containing no albumin (0.2 mM NaHCO₃, 150 mM NaCl, 2 mM CaCl₂, pH=7) in a Langmuir trough. On compression, the isotherm exhibits a characteristic shoulder at 45 mN/m and a collapse plateau at Π_max ~ 67 mN/m. On expansion, the surface pressure immediately drops to ~10–15 mN/m. The isotherms trace over each other on subsequent cycles.

(b) 800 µg lipid dispersion deposited onto an otherwise identical subphase containing 2 mg/mL albumin. The characteristic shoulder and collapse plateau on compression seen in (a) cannot be reached with albumin. The isotherms resemble that of albumin alone, shown in red, showing that lipid was prevented from adsorbing onto the interface ²⁶.