title: The lyophilization of dispersed systems: influence of freezing process, freezing time, freezing temperature and RBCs concentration on RBCs hemolysis.
abstract: In this work, we studied the influence of different parameters controlling cooling stage on biological dispersed system injury. The human red blood cell (RBCs) was chosen as work model. The study examined the influence of two freezing processes on RBCs hemolysis, one process producing big crystals, the other producing small crystals. Using both processes, we examined the effect of freezing temperature, freezing time, and RBCs concentration on injuries to RBCs. Freezing damage was assessed by the hematocrite measure before freezing and after thawing. The process producing a small number of big ice crystals (Pa) seems--in relation to the one producing a large number of small ice crystals (Pb)--to be less traumatic for the RBC, although the two are not statistically different. Freezing temperature and freezing time influence the preservation of RBCs. At 0 and -20 degrees C there were high preservation and total hemolysis, respectively. At -5 degrees C and -10 degrees C, the RBC hemolysis depends on freezing temperature and freezing time. The RBCs hemolysis rates increases when freezing time increases and when freezing temperature decreases. The rates of RBCs preserved decreases with RBCs concentration some with either the freezing process used (Pa or Pb). More, an accentuation of the difference between the two used freezing processes on RBCs hemolysis was retrieved. The analysis of the conductivity evolution within the RBCs suspension frozen showed that the destruction of the RBCs is had essentially to the solution effects. When the crystallization eutectic takes place, the RBCs are already completely destroyed.
authors.affiliation: Laboratoire de Pharmacie Galénique et Pharmacotechnie Industrielle, Université Mohammed V, Faculté de Médecine et de Pharmacie Rabat, Morocco.
authors.forename: Y
authors.initials: Y
authors.lastname: Bensouda
authors.forename: A
authors.initials: A
authors.lastname: Laatiris
mesh_terms: D001793:Blood Preservation; D015925:Cryopreservation; D004912:Erythrocytes; D005612:Freeze Drying; D005615:Freezing; D006461:Hemolysis; D013696:Temperature; D013997:Time Factors