Enthalpy relaxation behavior of DMSO/sucrose solutions (S1–4) at different temperatures below the T_g of the solutions.

<p>DSC pans with solution were maintained ~0–15°C below T_g for up to 300 min, after which thermograms were recorded (A–D). Enthalpy relaxation is evident as an endothermic event (oriented upwards) on top of the glass transition event, increasing with storage duration while decreasing if further from T_g. The area of this event, ΔH_relaxation, was determined and plotted versus the storage duration (E–G), for the indicated storage temperatures. Solution S1 was composed of 5% v/v DMSO, 1 M sucrose (A,E), S2 of 10% v/v DMSO, 1 M sucrose (B,F), S3 of 5% DMSO, 0.5 M sucrose (C,G), and S4 of 10% v/v DMSO with 0.5 M sucrose D,H).</p

CF leakage rates of PC liposomes with trapped CF in DMSO/sucrose solutions at different subzero temperatures.

<p>The difference between the storage temperature and T_g was plotted against the CF leakage rate. Cryoprotective solutions that were tested: 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).</p

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).</p

Glass transition temperatures of solutions composed of different contents of DMSO and sucrose.

<p>The onset temperature of glass transition was determined using DSC. This was done for 0–20% (v/v) DMSO solutions without supplements (white circles), as well as supplemented with 0.5 M sucrose (grey circles) or 1 M sucrose (black circles). For liposome storage experiments, performed at −80°C (dotted line), four different formulations were selected (labeled S1–4). Solution S1 was composed of 5% DMSO with 1 M sucrose (T_g: −68°C), S2 of 10% DMSO with 1 M sucrose (T_g: −77°C), S3 of 5% DMSO with 0.5 M sucrose (T_g: −84°C) and S4 of 10% DMSO with 0.5 M sucrose (T_g: −101°C).</p

Water fraction distributions in solutions composed of DMSO and sucrose, determined from the OH-stretching band in FTIR spectra.

<p>In panel A–B, the 3900–2700 cm⁻¹ spectral region is shown for two DMSO/sucrose solutions (S4: 10% v/v DMSO with 0.5 M sucrose, S2: 10% v/v DMSO with 1 M sucrose). Contributions of different water fractions were fitted, as Gaussian profiles centered initially at 3139 cm⁻¹ (fully hydrogen bonded water), 3241 cm⁻¹ (symmetrically hydrogen bonded water), 3389 cm⁻¹ (asymmetrically hydrogen bonded water) and 3533 cm⁻¹ (weakly hydrogen bonded water). The relative shifts in peak positions (C,D) and relative band areas (E,F) of these contributions were determined as a function of the DMSO concentration, in combination with either 0.5 M sucrose (C,E) or 1 M sucrose (D,F).</p

Parameters describing molecular mobility in glasses were determined by fitting DSC data on enthalpy relaxation versus storage.

<p>This was done for solution S1 (5% v/v DMSO, 1 M sucrose, white circles), S2 (10% v/v DMSO, 1 M sucrose, black circles), S3 (5% v/v DMSO with 0.5 M sucrose, white triangles) and S4 (10% v/v DMSO with 0.5 M sucrose, black triangles). In panel A, for S1–4, the natural logarithm of the relaxation time is plotted versus the difference between the storage temperature and T_g. In the panel B, data are presented in Arrhenius plots for deriving activation energies. The dotted line indicates −80°C.</p

Use of sucrose to diminish pore formation in freeze-dried heart valves

Abstract: Use of sucrose to diminish pore formation in freeze-dried heart valves