The properties research of polymerized human placenta hemoglobin before and after lyophilization

In this study, lyophilization was applied to polymerized human placenta hemoglobin (PolyPHb) solution. The lyophilization process was carried out with freezing at - 70°C for 5 h and two phases of drying: the first phase of drying was carried out at -35°C-35°C for 16 h and the second phase at 35°C for 8 h. Hemoglobin (Hb) concentration, methemoglobin (MetHb) content, oxygen-carrying capacity, Fe(3+) content, pH, UV spectrum, average molecular weight and its distribution, circular dichroism, SDS-PAGE, P50, crystal osmotic pressure, colloid osmotic pressure, zeta potential, average particle size, and other indicators were measured before and after lyophilization. Residual water content and rehydration time of the lyophilized products were also evaluated. All the indicators of lyophilized samples showed that the physical and biochemical properties of PolyPHb are not markedly changed before and after lyophilization. In this light, lyophilization may be a promising method for the preservation of PolyPHb solution.