Storage stability of PC liposomes with trapped CF, frozen in DMSO/sucrose solutions and stored at different temperatures.

<p>Cryoprotective solutions tested were: S1 (5% DMSO, 1 M sucrose, white circles), S2 (10% DMSO, 1 M sucrose, black circles), S3 (5% DMSO with 0.5 M sucrose, white triangles), and S4 (10% DMSO with 0.5 M sucrose, black triangles) HEPES buffered solution without further supplements (grey squares) served as a control. Samples were stored at −150°C (A), −80°C (B) and −25°C (C) for up to 3 months. As a measure for storage stability, CF-retention (i.e. protection against membrane leakiness) was assessed and plotted versus the storage duration. The insets in the panels (A) and (B) show the CF-retention after 90 d at −150°C and −80°C, respectively (no significant differences in CF-retention were found among the formulations). Data points representing mean values ± standard deviations were calculated from four measurements (control samples were measured once).