Magnetoliposomes with high USPIO entrapping efficiency, stability and magnetic properties

The DRV technique (followed by extrusion) was used for construction of hydrophilic-USPIO encapsulating liposomes. Magnetoliposomes (ML) were characterized for size, surface charge, entrapment, physical stability and magnetic properties (relaxivity). Results show that nanosized extruded-DRV MLs encapsulate higher amounts of USPIOs in comparison with sonicated vesicles. Fe (III) encapsulation efficiency (EE) is 12%, the highest reported to date for nanosized MLs. EE of MLs is influenced by ML membrane composition and polyethyleneglycol (PEG) coating. PEG-coating increases ML EE and stability; however, r2-to-r1 ratios decrease (in comparison with non-PEGylated MLs). Most ML-types are efficient T2 contrast agents (because r2-to-r1 ratios are higher than that of free USPIOs). Targeted MLs were formed by successfully immobilizing OX-26 monoclonal antibody on ML surface (biotin-streptavidin ligation), without significant loss of USPIOs. Targeted MLs retained their nanosize and integrity during storage for 1 month at 4°C and up to 2 weeks at 37°C.From the Clinical EditorSkouras and colleagues present a method for high encapsulation of hydrophilic USPIO-s in magnetoliposomes using the DRV extrusion technique. The goal is to optimize the production of MRI detectable contrast agents with functionalized homing capability based on immobilizing specific antibodies in the surface of magnetoliposomes.

Graphical AbstractHigh encapsulation of hydrophilic-USPIOs in MLs by DRV-extrusion technique. Stability increases by PEGylation, however magnetic properties may decrease, depending on lipid composition. Immobilization of MAb on MLs achieved without size increase or loss of USPIOs. TEM images. A, B: Control MLs (no MAb); C: empty immuno-MLs and D-F: immuno-MLs. All after immunogold staining].Figure optionsDownload high-quality image (169 K)Download as PowerPoint slide