Diffusion limited field induced aggregation of magnetic liposomes

Magnetic liposomes are spherical vesicles containing magnetic particles. Their practical interest relies in their potential use as "intelligent" drug delivery systems, with magnetic driving or targeting possibilities. In the presence of a field, the vesicles become magnetized and interact. A strong interaction leads to aggregation and could in extreme lead to undesirable clogging in physiological conditions. We investigated the formation of chain aggregates in liposome dispersions in the presence of magnetic fields by light scattering measurements. Data analysis showed that aggregation number increased linearly with elapsed time, as for ordinary isotropic colloid diffusion limited aggregation. The rate of aggregation increased with the field also linearly for low field strengths, and saturates at higher fields. These results are in contrast with measurements for the pure magnetic fluid, i.e., non-encapsulated magnetic particle dispersions