Optical cryomicroscopy and differential scanning calorimetry of buffer solutions containing cryoprotectants

In the pharmaceutical industry, cryoprotectants are added to buffer formulations protect active ingredient from freeze- and thaw damage. We investigated freezing thawing of aqueous sodium citrate with various cryoprotectants, specifically amino acids (cysteine, histidine, arginine, proline lysine), disaccharides (trehalose sucrose), polyhydric alcohols (glycerol mannitol) surfactants (polysorbate 20 polysorbate 80). Hereby, we employed optical cryomicroscopy in combination differential scanning calorimetry temperature range −80 °C. The effect on morphology ice crystals, glass transition initial melting is presented. Some have a significant impact crystal size. Disaccharides restrict growth, whereas glycerol allow crystals increase Cysteine mannitol cause dehydration after thawing. Either one or two temperatures were detected, where surfactants, glycerol, lysine suppress second, implying uniform freeze-concentrated solution. pure solution can be shifted up by adding mannitol, both surfactants; but down lysine.