Magnetoliposomes with high USPIO entrapping efficiency, stability and magnetic properties
De Goltstein, Marie Christine
Antimisiaris, Sophia G.
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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, r 2-to-r 1 ratios decrease (in comparison with non-PEGylated MLs). Most ML-types are efficient T2 contrast agents (because r 2-to-r 1 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 Editor: Skouras 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.