Oxygen-carrying artificial blood solutions have been sought for over a century. There have been continuous studies to develop a safe intravenous acellular oxygen-carrying solution that would mimic the function of red blood cell (RBC) in supplying oxygen to the tissues. Today, there are approximately 4 million patients in the U.S., and about 8 million patients worldwide each year, expecting to receive two or more units of blood during cardiovascular, orthopedic, urologic, and general surgical procedures. Although the blood donations are increasing yearly in the U.S., it is not sufficient to meet the increasing demand as an aging population requires more operations that involve blood transfusion. In addition, allogeneic blood transfusions often bear risk factors and disadvantages such as infectious transmission posed by blood-born pathogens, increased mortality or morbidity from postoperative wound infections, short shelf-life of stored blood, and immunosuppressive effects that may follow blood transfusion. In an attempt to relieve these complications and to sufficiently supply the demand, artificial blood has been developed as a substitute for red blood cells, for the sole purpose of transporting oxygen and carbon dioxide throughout the body. Depending on the type of artificial blood, it can be produced in different ways using synthetic production, chemical isolation, or recombinant biochemical technology.