These investigators propose to design and synthesize a series of bifunctional organic reagents which contain negatively charged functional groups and range of specific molecular tether lengths. These bifunctional organic reagents are for chemically modifying cell-free human hemoglobins for use as oxygen carrying blood substitutes in emergency transfusions. These artificial oxygen carriers would be free of HIV and other transfusion-transmitted infectious agents. The investigators will verify molecular structures configuration, conformation and tether length of the newly synthesized reagents and then explore the reagents' potential to form covalent bonds with natural amino acids lysine cysteine valine in aqueous media. The modified hemoglobins will be purified and their physical composition and functional properties will be investigated.