Stable clusters in liposomic systems

Abstract

The formation of stable clusters in colloidal systems is usually explained by the combination of a short ranged attractive force and a repulsive force with an interaction range in the order of the colloidal particle size. Using light scattering techniques we studied five different liposomic systems undergoing aggregation through five different mechanisms: aggregation by charge neutralization, DLCA and RLCA by charge screening, aggregation in a secondary minimum, depletion attraction and “patchy” electrostatic interactions. Surprisingly, three of these systems lead to the formation of stable clusters despite the Debye length of the electrostatic repulsion being less than 5% of the diameter of the liposomes. Alternative explanations for the stabilization of the clusters are discussed using non-DLVO forces. The understanding and controlling of the formation of stable clusters of liposomes may have an important impact in their application as a drug delivery system.