Preparation of PEG-liposomes and Ni 2? NTA liposomes A mixture of 2.5 lmol of total lipids (EPC, CHOL and DSPE-PEG 5000 with a molar ratio of EPC:CHOL:PEG Fig. 1 Schematic representation of AnExIL formulations used in this study 5000 = 1.6:0.9:0.025) or (EPC, CHOL, DOGS-NTA) with a molar ratio of EPC:CHOL:DOGS-NTA = 1.55:0.9: 0.025) were dissolved in dichloromethane:diethylether (1:1, v/v) in a round bottom flask. A thin, dry lipid film was obtained after evaporating the solvents using a rotary evaporator under vacuum at 30°C and subsequently dried with nitrogen for 30 min. The lipid film was hydrated in distilled water by shaking using glass beads to form large multilamellar liposomes, further sonicated with a probe sonicator to produce unilamellar liposomes. The liposomes suspensions were divided into 100 ll aliquots in 1.5 ml tubes (6 lm of total lipids/batch), freeze-dried and the obtained lyophilized lipid cakes were stored in a desiccator at room temperature until used.