Liposome Preparation for Comparative Studies

Liposomes used in this study contain a 4:4:2:0.5:0.01 molar ratio of 1,2,dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (POPC), cholesterol, total ganglioside extract (TGE) and Oregon green DHPE, based on compositions found in previous studies that provide comparative data19 21 (link). The lipids were purchased from Avanti Polar Lipids (Alabster, AL), and Oregon green DHPE was purchased from Molecular Probes, Eugene, OR. To form liposomes, all components were dissolved and mixed in biotechnology grade chloroform (Sigma-Aldrich) in a glass vial. The bulk solvent was first removed by blowing high purity nitrogen and the solution was placed in a desiccator under vacuum for 3 h to ensure complete evaporation of the solvent. GPMV buffer (50 mM Hepes, 150 mM NaCl, 2 mM CaCl₂, pH 7.4) was then added to the vial to re-suspend the dried lipid film to create a 5 mg/mL solution. Liposomes were then extruded ten times through a 100 nm pore size polycarbonate filter (Whatman Nucleopore), and five times through a 50 nm pore size filter.