THE EFFECT OF MOLECULAR-DIFFUSION ON INITIAL PARTICLE-SIZE DISTRIBUTIONS IN PHOSPHOLIPID-STABILIZED FLUOROCARBON EMULSIONS

Molecular diffusion is shown to be the key determinant of initial particle size in fluorocarbon emulsions stabilized by egg yolk phospholipids. Whereas droplet sizes of approximately 0.2 mum are achievable with perfluorooctyl bromide (PFOB) as the dispersed fluorocarbon phase, less than 0.1 mum droplets may be obtained for mixtures of PFOB and perfluorodecyl bromide (PFDB). PFDB, being virtually insoluble in the continuous water phase, serves to inhibit molecular diffusion by reducing the water solubility of the dispersed phase in small droplets of a polydisperse dispersion. The achievement of small emulsion droplet sizes aids in improving the biocompatibility of fluorocarbon emulsion formulations intended for use as injectable oxygen carriers or contrast agents.