Lipid-based assemblies are the most studied systems for the delivery of nucleic acids for therapeutic purposes. Fundamental research has been directed to the elucidation of the structural features of lipid-DNA assemblies in relation with the experimental conditions, the chemical nature of the lipids and of the nucleic acids. However, the design of efficient nanostructured vectors, implies the comprehension of their behavior in biologically relevant media and interaction with cell mimic systems.
In this contribution we report on the nucleolipid liposomes-DNA complexes (nucleolipoplexes), from the anionic nucleolipid POP-Ade (1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol) mixed with two zwitterionic helper lipids, POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine).
We investigated the interaction between POP-Ade nucleolipoplexes and Giant Unilamellar Vesicles (GUVs), taken as cell membrane models through Confocal Microscopy (LSCM) and Fluorescence Correlation Spectroscopy (FCS).
First, we studied the morphology and the structure of nucleolipoplexes through the diffusion of a lipid probe embedded within nucleolipoplexes’ lipid structure and of a lipid tag attached to the complexed DNA.
Then, we monitored in real time through LSCM the interaction between nucleolipoplexes and GUVs and membrane fusion occurrence was found dependent on the nucleolipoplexes’ liquid crystalline structure and on the surface charge of the target model membrane.
Finally, we carried out FCS studies on the diffusion of fluorescently-labeled lipids and of fluorescently-labeled DNA in nucleolipoplexes-GUVs interaction regions, and on the penetration of fluorescently-labeled DNA inside the GUVs’ lumen upon interaction with nucleolipoplexes. The dynamic information on lipid exchange and of DNA diffusion allowed us to elaborate possible hypothesis on the structure of the fusion intermediates and on the interaction pathway between nucleolipoplexes and GUVs from surface interaction, to membrane fusion, to DNA release inside the GUVs.
Costanza Montis, Piero Baglioni, Debora Berti Soft Matter, 2014, 10, 39
piero.baglioni@unifi.it
