Structural transition in aqueous lipid/bile salt [DPPC/NaDC] supramolecular aggregates: SANS and DLS studyстатья
Информация о цитировании статьи получена из
Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Авторы:Kiselev M.A.,
Janich M.,
Hildebrand A.,
Strunz P.,
Neubert R.H.H,
Lombardo D.
Аннотация:Aqueous bile salt - phospholipid mixtures become more significant as model systems for the investigations of the self-assembly of amphiphilic molecules and the solubilization process in bio-membranes. Small angle neutron scattering (SANS) was used to study the different aggregation states in sodium deoxycholate (NaDC)-phosphatidylcholine systems at T = 60°C. Additionally, dynamic light scattering (DLS) was applied. The size and the shape of the aggregates, occurring in the vesicle to micelle transition, were investigated as a function of the NaDC bile salt concentration at the constant DPPC concentration of 6 mM. The interpretation of the SANS spectra, performed by means of suitable vesicles and micelles models for the form factor which take into proper account the particles polydispersity, indicate a strong dependence of the size and morphology of the generated supramolecular aggregates on the relative amount of NaDC bile salt. More specifically the adopted models identifies the formation a rich variety of supramolecular structures ranging from ellipsoidal vesicles (1.5 mM NaDC), ribbon-like structure (at 3.5 mM NaDC), up to final spherical mixed micelles at large amount of bile salt (10 mM NaDC). Interestingly, at intermediate bile salt concentrations (i.e. for 5.5 mM and 7.5 mM NaDC) SANS data indicate the coexistence of two morphology in the system consisting of rod-like micelles (with spherical cross-section) and ellipsoidal micelles. In this case SANS analysis indicate that the concentration of ellipsoidal micelles increases 10 times with the increased NaDC bile salt concentration passing from 5.5 mM up to 7.5 mM. In this respect large occupied area of the bile salt promote a steric interaction with the enlargement of the average aggregate headgroup area, and the transition from of large elongated structures (ellipsoidal vesicles or elongated micelles) toward more stable and compact spherical micelles. The finding of the obtained results give important insight for understanding the formation of intermediate structures and different topologies in aqueous lipid-bile salt mixtures as well as stimulate new routes for liposome reconstitution and solubilisation processes suitable for biotechnological applications.