PHOSPHATIDYLCHOLINE VESICLE DIAMETER, MOLECULAR-WEIGHT AND WALL THICKNESS DETERMINED BY STATIC LIGHT-SCATTERING

Phosphatidylcholine vesicles in the diameter range, 40 to 115 nm scatt er light as isotropic hollow spheres within the Rayleigh-Gans-Debye (R GD) approximation. A more complex model (i.e., the exact or Lorenz-Mic theory) is not required for accurate interpretation of the static lig ht scattering data. The scattered light intensity measurements also al low for the determination of the vesicle weight-average molecular weig ht through a Zimm plot analysis. This information, in combination with the vesicle size as determined within the RGD approximation, indicate s that the vesicle wall thickness is close to 3.6 nm as previously det ermined by X-ray diffraction methods. Thus, static light scattering te chniques may provide excellent estimates of surfactant vesicle wall th icknesses. (C) 1994 Academic Press, Inc.