Fluorinated materials for in vivo oxygen transport (blood substitutes), diagnosis and drug delivery

Fluorocarbons are characterized by exceptional chemical and biological inertness, extreme hydrophobicity, lipophobicity, high gas-dissolving capacities, low surface tensions, high fluidity and spreading coefficients, high density, absence of protons, and magnetic susceptibilities comparable to that of water. These unique properties are the foundation for a range of biomedical applications. An injectable fluorocarbon-in-water emulsion is in advanced clinical trials as a temporary oxygen carrier (blood substitute) to prevent tissue hypoxia or ischemia in the surgical and critical care patient. A liquid fluorocarbon is in Phase II/III clinical trials for treatment of acute respiratory failure through liquid ventilation. Several fluorocarbon-based contrast agents for ultra-sound imaging are in various stages of clinical investigation. Multiple families of well-defined pure fluorinated surfactants have recently been synthesized. These surfactants have a modular structure which allows stepwise adjustment of their physicochemical characteristics. Their polar head group derives from polyols, sugars, aminoacids, amides, amine oxides, phosphocholine, phosphatidylcholine, etc. Fluorinated surfactants are significantly more surface-active than their hydrocarbon analogs and they display a greater tendency to self-assemble, thus forming well-ordered, stable supramolecular assemblies such as vesicles, tubules, fibers, ribbons, etc. Fluorinated amphiphiles also allowed the obtaining of a variety of stable reverse and multiple emulsions and gels. These systems are being investigated as drug delivery devices.