Preparation and stability of liposome-type artificial red blood cells stabilized with carboxymethylchitin

Liposome-type artificial red blood cells stabilized with carboxymethylchitin (mean diameter 310 nm) were prepared by a two-step emulsification technique. Sheep haemolysate was dispersed as fine droplets in a lecithin solution in dichloromethane to yield a W/O-type emulsion. The W/O emulsion thus obtained was then dispersed in an aqueous carboxymethylchitin solution to give a W/O/W-type complex emulsion. Removal of the organic solvent by evaporation from the complex emulsion left an aqueous suspension of the artificial red blood cells. The haemoglobin-trapping efficiency of the cells was found strongly dependent on the pH of the carboxymethylchitin solution used. The artificial red blood cells underwent disintegration by the action of surfactants. When a comparison was made among those surfactants which have the same alkyl chain length, the degree of cell disintegration was in the increasing order, anionic greater than cationic greater than nonionic. Globulin and fibrinogen produced no disintegration of the cells while albumin disrupted the cells to a slight extent.