Blood substitutes and other potential biomedical applications of fluorinated colloids

An oxygen carrying, heat-sterilized phospholipid-based emulsion of a fast excreted lipophilic fluorocarbon, perfluorooctyl bromide (perflubron), stabilized against molecular diffusion, has been developed to serve as a temporary blood substitute. It is expected to reduce exposure to donor blood and thereby help mitigate the pressure on our blood supply. A phase III clinical trial in Europe has demonstrated that use of the emulsion resulted in avoidance and reduction of donor blood transfusion in surgery patients. Further potential applications for fluorocarbon emulsions include use as a bridge to transfusion, treatment of myocardial ischemia and stroke, potentiation of radio and chemotherapy and preservation of organs destined for transplantation. Echogenic, injectable gaseous microbubbles, osmotically stabilized by perfluorohexane, provide an effective contrast agent for ultrasound imaging. Clinical trials have established improved imaging of the walls of the heart and, hence, assessment of cardiac function. The ability of improving detection of myocardial perfusion, blood flow abnormalities and solid tumors is also being investigated. Various families of fluorinated amphiphiles with modular molecular structures and polar heads derived from natural products have been synthesized. Due to their highly hydrophobic perfluoroalkylated tail chains, these amphiphiles readily self-assemble into stable fluorinated vesicles, tubules and other organized molecular systems with distinctive properties. Fluorosurfactants also allowed preparation of direct, reverse, apolar and multiple emulsions and gels. These fluorinated colloids have potential for the delivery of drugs and other bioactive materials, and provide unique tools in biomedical research.