Structure and interfacial properties of phospholipid-containing sponge nanoparticles and their interaction with myoglobin.

HYPOTHESIS: Sponge phase (L3) lipid nanoparticles (L3-NPs) have been shown to have large potential for the encapsulation of biomolecules, such as enzymes, with applications in food and pharmaceutical science. In this study, we introduce new formulations of L3-NPs including the phospholipids dioleoylphosphatidylcholine (DOPC) and dioleoyltrimethylammonium propane (DOTAP). The interaction of these new L3-NPs with myoglobin is of interest for the development of iron supplements which can be incorporated during food processing.

EXPERIMENTS: We characterized the sample structure by small-angle X-ray scattering (SAXS) measurements with and without the addition of myoglobin. We also tested the myoglobin-lipid interaction in an experimental setup that mimicked the interface between the bilayer and water channels within the bicontinuous sponge structure. This included spreading the L3-NPs onto a hydrophilic surface to form supported lipid bilayers and characterizing their interaction with myoglobin by means of quartz crystal microbalance with dissipation monitoring and polarized neutron reflectometry.

FINDINGS: SAXS data indicate that the new formulations containing DOPC and DOTAP formed a sponge phase in the bulk. The data from the surface techniques showed that deposited bilayers containing DOPC were largely unaffected by the addition of myoglobin, whereas those without DOPC were destabilized and partially removed.