The 1,2-distearoryl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol-2000)] ammonium salt (DSPE-PEG), dioleoyl phosphatidic acid (DOPA) and 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP) were purchased from Avanti Polar Lipids (Alabaster, AL). The DSPE-PEG-AEAA was synthesized according to previous publication of our lab.58 (link) Doxorubicin, cholesterol and protamine were purchased from Sigma-Aldrich (St. Louis, MO). DiI was purchased from ThermoFisher Scientific (Waltham, MA).