Released dextran-containing liposome suspension was centrifugated with Nanosep Omega 100K filtration tube (Pall, Port Washinton, NY, USA) at 3000 ×g at 4°C and washed with PBS for three times to remove leaked dextran. After that, fluorescence intensity at 600 nm and 540 nm for the suspension was measured. Relative amount of cargo dextran in the liposomes was calculated from the ratio of fluorescence intensity of NBD unit in the liposomes (em = 540 nm, I540) and Antonia red labelled with dextran (em = 600 nm, I600). Therefore, the ratio of fluorescence intensity of NBD and Antonia red, I600 / I540, is a constant value if any dextran is not leaked from liposomes. When the leakage occurs, I600 / I540 should decrease because leaked dextran could be removed by the filtration step. We calculated the cargo remaining (%) as I600 / I540 ratio between the liposomes after release procedure and ones without any treatment as follows: