Application of Evanescent Wave Scattering to the Study of the Motion of Liposomes near a Solid Surface

Abstract

This report presents measurements and calculations of dynamic light scattering of evanescent waves from negatively and positively charged liposomes diffusing near a glass-solution interface. Scattering from the glass interface provides the reference beam for heterodyne detection. The measured short time decay of the autocorrelation functions for negatively charged liposomes is consistent with the response calculated using a model with unrestricted diffusion in half space with reflecting boundary conditions at the glass interface. In contrast, positively charged liposomes show significant deviations from the model predictions. In both cases, the short time response is significantly slower than the bulk value. The diffusion coefficient of negatively charged liposomes is nearly independent of the scattering angle. The technique gives information on the effects of "association" with the interface on the diffusive motion near an interface.