Until the FDA Rescinded the Permit for Its Use in 2002

Essay

Until the FDA rescinded the permit for its use in 2002, perflubron, a mixture of 1-bromoperfluorooctyl bromide [CF₃(CF₂)₆CF₂Br] and 1-bromoperfluoroodecyl bromide [CF₃(CF₂)₈CF₂Br], was being investigated for possible use as artificial blood during surgery. Perflubron dissolves substantial amounts of oxygen; a mouse can breathe when submerged in oxygenated perflubron. Perflubron is completely insoluble in water. To make it compatible with the aqueous biological environment, it had to be suspended in water in such a way that it would form an emulsion and not separate into layers. (In an emulsion, water-insoluble substances are suspended as small particles that do not form a separate layer.) Addition of lecithin, a phospholipid from egg yolks, met this objective.
Explain the action of lecithin. As part of your explanation, use a diagram to propose a general structure of a perflubron-containing particle.