Rhodamine b dhpe

Pegylated liposomes, composed with HEPC (Hydrogenated Egg Yolk Phosphatidylcholine), CHOL (Cholesterol) and DSPE-PEG₂₀₀₀ (Methoxypolyetheleneglycol (Mw 2000)-distearylphosphatidylethanolamine) (185:1.00:015, molar ratio), were prepared as previously described by Zucker et al. (2009) (link). Briefly, the lipids were dissolved in chloroform, and after evaporation of the organic solvent with rotary evaporator (Büchi Rotavapor R-215, Switzerland) under reduced pressure at room temperature. The resulting lipid film was hydrated at 70 °C in 250 mM ammonium sulfate (pH5.4) to form multilamellar vesicles (MLV). The liposome size was reduced by stepwise extrusion in two steps, firstly through 0.2 μm and then through 0.1 μm pore-diameter polycarbonate filters (Whatman, Maidstone, Kent, UK). Each extrusion step was performed 5–10 times at 70 °C using a high-pressure extruder (Northern Lipids, Inc. Burnaby, BC, Canada).
The mean diameters of the resulting liposomes were determined by photon correlation spectroscopy (PCS) on a Malvern Zetasizer (Zetasizer Nano ZS Zen 3600, Malvern instruments, UK) at 25 °C, using water as the dispersant. Three measurements were taken on each sample.
In the aim to study interaction between liposomes and H9c2 cells, fluorescent liposomes were prepared following the same steps but with the addition of 1% of Rhodamine B-DHPE (Sigma) to the lipid mixture.