Artificial Oxygen Carriers

Because of the increasing demand for blood and the emergence of unsafe issues in allogeneic blood transfusion, blood substitutes are attracting increasing interest in chemistry and medical science. Based on the knowledge of the structure and functions of hemoglobin-a typical natural oxygen carrier, many artificial oxygen carriers have been synthesized and applied to clinical trails. Artificial oxygen carriers include perfluorocarbon, hemoglobin-based oxygen carrier, synthetic heme and its polymer metal complexes. Although most of the perfluorocarbons could not be applied as blood substitutes, their applications as medicine are still continued because of their therapeutic effect. In order to reduce unwanted side-effects of hemoglobin-based oxygen carriers, hemoglobin has been modified by many methods, such as chemical modification, microencapsulation, recombinant technology, biomimetic nanotechnology,, etc. Among all of the above hemoglobin-based oxygen carriers, the particle size of hemoglobin vesicles (HbV) is relatively larger in the simulation of the structure of the red blood cell. It represents one of the tendency of the progress of hemoglobin-based oxygen carriers. Most of synthetic hemes, such as pocket porphyrin metal complexes, are only dissolved in organic solvents. In order to increase their water-solubility, synthetic hemes have been conjugated with albumin, xylitol enzymes and cyclodextrin and so on. The results of animal trial showed that these polymer metal complexes could transport dioxygen in the animal body. Beside to be used as the blood substitutes in clinical trails, artificial oxygen carriers have other potential clinical uses, such as cancer therapy, organ transplantation and prevention of ischemia/reperfusion injury of tissues and organs.