Morphology of bile salts micelles and mixed micelles with lipolysis products, from scattering techniques and atomistic simulations

Bile salts (BS) are biosurfactants released into the small intestine, which play key and contrasting roles in lipid digestion: they adsorb at interfaces promote adsorption of digestive enzymes onto fat droplets, while also remove lipolysis products from that interface, solubilising them mixed micelles. Small architectural variations on their chemical structure, specifically bile acid moiety, hypothesised to underlie these conflicting functionalities, should be reflected different aggregation solubilisation behaviour. The micellisation two BS, sodium taurocholate (NaTC) taurodeoxycholate (NaTDC), differ by one hydroxyl group was assessed pyrene fluorescence spectroscopy, morphology aggregates formed absence presence fatty acids (FA) monoacylglycerols (MAG) – typical resolved small-angle X-ray/neutron scattering (SAXS, SANS) molecular dynamics simulations. BS triacylglycerol-incorporating liposomes mimicking ingested lipids studied neutron reflectometry SANS. Our results demonstrate micelles exhibit an ellipsoidal shape. NaTDC displays a lower critical micellar concentration forms larger more spherical than NaTC. Similar observations were made for with FA MAG. Structural studies show addition induces micelles, displaying higher capacity.