Flow properties of hemolysate-loaded liposome suspensions.

Sheep hemolysate-loaded liposomes were prepared by a modified interfacial deposition technique. The mean diameter of the liposomes was estimated to be about 310 nm. Sheep hemolysate-loaded liposomes were called artificial red blood cells (ARBC). The flow properties of the ARBC suspension (pH 7.4) were measured with a concentric cylinder-type rorational viscometer at low shear rates and were compared with those of sheep red blood cell (SRBC) suspension (pH 7.4). It was revealed that the flow type of the ARBC suspension (pH 7.4) was of pseudoplastic as in the case of SRBC suspension (pH 7.4). The relative viscosity of the ARBC suspension as a function of particle concentration in the medium was linear and fitted fairly well with the Einstein equation. However, the relative viscosity of SRBC suspension was increased more gradually with increasing particle concentration, and was well presented by the Brinkman equation as a function of particle concentration for concentrated suspensions. It was suggested that this would be due to the difference in particle-particle interaction between the two types of suspensions. The flow properties of the mixed suspensions of the ARBC and SRBC in the suspending medium (pH 7.4) with and without dextran were measured. It was revealed that the relative viscosity of the mixed suspension is reduced with increasing mixing ratio of the ARBC in the suspension, suggesting that the flow properties of the mixed suspension of the ARBC and SRBC are dependent on the ARBC rather than dextran.