APPLICATION OF EVANESCENT-WAVE SCATTERING TO THE STUDY OF THE MOTION OF LIPOSOMES NEAR A SOLID-SURFACE

This report presents measurements and calculations of dynamic light sc attering of evanescent waves from negatively and positively charged li posomes 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 ne gatively charged liposomes is consistent with the response calculated using a model with unrestricted diffusion in half space with reflectin g boundary conditions at the glass interface, In contrast, positively charged liposomes show significant deviations from the model predictio ns, In both cases, the short time response is significantly slower tha n the bulk value, The diffusion coefficient of negatively charged lipo somes is nearly independent of the scattering angle. The technique giv es information on the effects of ''association'' with the interface on the diffusive motion near an interface. (C) 1995 Academic Press, Inc.