Two phase formation in pharmaceutical and fine chemicals

Abstract

Two phase formation (liquid-liquid phase separation) during cooling crystallization of hen egg-white Lysozyme (HEWL) and the effect of that phenomenon on crystal properties were studied. Two phase formation in Lysozyme solutions was observed as the formation of protein-rich droplets (protein-rich phase) dispersed in the matrix of continuous phase (protein-lean phase) when the solutions were cooled to low temperature (less than 10A?C). Onset of the cloudiness of Lysozyme solutions during phase separation was determined as the cloud point temperature (Tcloud) and sets of Tcloud form the cloud point curve of Lysozyme system. Spherically-shaped Lysozyme crystals were obtained during phase separation. These crystals were different in shape as compared to the well-known tetragonal and orthorhombic crystals. Crystals formed via two phase formation (spherically-shape or spherical transformed tetragonal crystals) were uniform in size and had a narrower crystal size distribution as compared to the crystals formed in solutions without passing through two liquid-phase region.