Ionic environment, thickness and line tension as determinants of phase separation in whole Purified Myelin Membranes monolayers

PUSTERLA, JULIO; HERNANDEZ, JUAN MARTIN; WILKE, NATALIA; SCHNECK, EMANUEL; OLIVEIRA, RAFAEL G.

COLLOIDS AND SURFACES B-BIOINTERFACES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021 vol. 207 p. 112027 - 112027

0927-7765

urified myelin membranes (PMM) were spread as monomolecular films at the air/aqueous solution interface,and visualized by Brewster Angle Microscopy (BAM) at different lateral pressures ( π ) on three specific aqueoussolutions: absence of salts, physiological conditions and presence of calcium. Coexistence of Liquid-Expanded(LE) and Liquid Ordered (LO) phases persisted up to collapse in the presence of salts, whereas monolayersbecame homogeneous at π ≥ 35− 40 mN/m when salts are absent. This PMM phase-mixing behavior in mono­layers is similar to the previously reported behavior of PMM multilamellar vesicles. Reflectivities (R p ) of p-polarized light from both phases were assessed throughout the whole π -range, and film thicknesses (t) werecalculated from the R p values and measured film refractive indices (n). The LO phase was found to be morereflective and thicker than the LE phase at π ≤ 15 mN/m, but less reflective and thinner at higher π