orb the oxygen when the red blood cell passes through the lungs. As hemoglobin travels the 100,000 miles of veins inside the body, it releases oxygen as the constant source for the whole body. The exact process of how the hemoglobin absorbs and releases oxygen into the body is a very complex process and scientists have not yet been able to completely understand it; however, the Bio-tech companies have tried to equal this process (Cannell 1999)1. The Bio-tech companies must keep in mind the following criteria while synthesizing an ideal blood substitute: (i) require no cross-matching or compatibility testing, (ii) be suitable for long term storage (preferably at room temperature), (iii) be able to survive in the circulation for several weeks (the intravascular "dwell" time) before being cleared by the kidney, (iv) be free of side effects, (v) be free of pathogens, and (vi) not only transport but also effectively deliver oxygen to the tissues (Squires 2002)3.
             There are primarily two basic routes these companies have taken to create artificial blood: the use of purified hemoglobins, otherwise known as hemoglobin-based oxygen carrier's (HBOC's) or the use of perfluorocarbons (PFC's). Three companies; Hemosol, Biopure, and Northfield experiment with purified hemoglobin as their means for obtaining artificial blood. Hemosol and Northfield obtain their hemoglobin from humans while Biopure experiments with hemoglobin obtained from bovines.
             Hemoglobin (Hb) is a tetramer, a protein in red blood cells that contains two á and two â polypeptide chains. Each of these chains is connected to an iron-containing heme group, and each heme group connects to one oxygen. Figure one shows the mechanism of the hemoglobin molecule. The red blood cell retains 2, 3 diphosphoglycerate (2, 3 –DPG). The 2, 3-DPG binds to the 2, 3-DPG pocket of the Hb molecule, which allows the hemoglobin to release the oxygen...