Microalgae-derived vesicles as potential carriers for therapeutic biomacromolecules

Microalgae-derived vesicles (AGVs) were investigated as potential carriers for therapeutic biomacromolecules. AGVs were prepared by rehydration of a lyophilisate of proteolipid ghost membranes from Dunaliella tertiolecta and subsequent extrusion or sonication. Based on our results, extrusion is suggested to be a more suitable method because of the low loss of the lipid and protein content. Applying small-angle neutron scattering and dynamic and electrophoretic light scattering, we found that the formed AGVs are spherical, unilamellar, with moderate polydispersity, and a negative surface charge of -27 mV. EPR findings show that they retain the membrane dynamics, and possibly the degree of lipid chain saturation, of the ‘mother’ algal cells. The drug-binding efficiency of the reconstructed AGVs was tested for two model biomacromolecules, DNA and BSA, using an ethidium bromide exclusion assay and tryptophane autofluorescence, respectively. The electrostatic interaction between AGVs and DNA polyanion was mediated by Ca 2+ ions, while for the interaction of BSA with AGVs hydrophobic interactions are assumed to play a dominant role. For both macromolecules tested, 40% binding of the total drug amount was achieved by passive incubation, which indicates that reconstructed AGVs might expand the repertoire of potential delivery systems for therapeutic biomacromolecules.