Structural transition in aqueous lipid/bile salt [DPPC/NaDC] supramolecular aggregates: SANS and DLS study

- Self-assembly in model DPPC lipids and NaDC bile salt by SANS and DLS experiments.
- Bile salt creates structural interference against cohesive tendency of DPPC bilayers.
- NaDC steric interactions cause transition toward different supramolecular structures.

Small angle neutron scattering (SANS) and dynamic light scattering (DLS) were used to study different aggregation states in sodium deoxycholate (NaDC)-phosphatidylcholine systems at T = 60 °C. Size and shape of the aggregates investigated as a function of the NaDC bile salt concentration (at the constant DPPC concentration of 6 mM) indicate a strong dependence of the size and morphology of the generated aggregates on the relative amount of NaDC bile salt. More specifically large occupied area of the bile salt induces a steric interaction which promotes the transition toward a variety of supramolecular structures ranging from ellipsoidal vesicles, ribbon-like structures, up to final spherical mixed micelles at the large amount of bile salt of 10 mM NaDC. The findings of the obtained results give important insight for understanding the formation of different topologies in aqueous lipid-bile salt mixtures as well as stimulate new routes for liposome reconstitution-solubilisation processes suitable for technological applications.