Charge and size dependence of liposome diffusion in semidilute biopolymer solutions

Abstract

The diffusion of liposomes and PL/DNA complexes in mucin and collagen solutions, considered to model 'in vivo' colloidal gene delivery vector transport, is studied with FCS. The diffusion of defined liposomes is investigated as a function of particle size, surface charge, and the deviation from the Stokes-Einstein behavior. In all cases the self-diffusion coefficient decreases exponentially with polymer concentration. The same surface charge dependence of diffusion is observed in mucin for PL/DNA complexes with either positive or negative excess charge. Incubation of positively-charged PL/DNA complexes in a natural lung surfactant lipid increases the diffusion coefficients to almost the same as for the negatively-charged PL/DNA complexes.