Rheological quantification of liposomes aggregation

Abstract

Aim. The aggregation of phospholipid vesicles (liposomes) in water is analyzed experimentally and theoretically and compared with the well-examined alumina dispersions. The steady-state aggregation followed rheologically for various volume fractions of particles and shear rates. Methods. A micro-rheological model of aggregating dispersions is proposed in which the apparent viscosity is estimated as the sum of hydrodynamic and structural parts, which are correlated with system structural ordering. Langevin equation is used to describe the dynamics of evolution of steady-states of liposome systems in phase space, for various shear rates. Results. These results established a link between the local dynamics of liposome dispersions and their flow behavior. Conclusion. Aggregates become more compact and embedded higher volume of fluid when shear rate increases. Hydrodynamic part of viscosity increases, while structural part of viscosity decreases with shear rate. Calculated value of bond energy between liposomes corresponds to hydrogen bond energy.