Structural Elucidation of Light Activated Vesicles

In the present study, synchrotron small-angle X-ray scattering (SAXS) combined with a UV light source (in situ SAXS-UV irradiation) was used to determine the structure response of gold nanoparticle (NP)-loaded vesicles. The investigated system consisted of multilamellar vesicles of N-methylated dioleoylphosphatidylethanolamine (DOPE-Me) containing hydrophilic gold NPs with a size of 40 Å. Our results indicate drastic optothermically induced structural changes in these gold NP-loaded aqueous dispersions, which are accompanied by strong alterations in the phospholipid membrane permeability. A structural mechanism from well-ordered multilamellar vesicles in the fluid lamellar (L α ) phase to an inverted type hexagonal liquid crystalline (H 2 ) phase via the formation of an intermediate phase of uncorrelated fluid bilayers is proposed. In general, these investigations are also crucial for the understanding of the potential of gold NP-loaded model phospholipid systems as efficient drug nanocarriers aiming to improve drug targeting and releasing on demand.