Fluorous micro- and nanophases with a biomedical perspective

Abstract

Fluorinated components useful for organizing space at the molecular, nanometer and micrometer scales include perfluorocarbons, perfluoroalkylated surfactants and perfluoroalkyl/alkyl diblock amphiphiles. Perfluoroalkyl moieties, being lipophobic as well as highly hydrophobic, add a new dimension to the hydrophobic segregation effect. Fluorinated amphiphiles, therefore, have an enhanced tendency to self-assemble in various media into stable, highly organized fluorinated colloids, thus generating organized nanometer-size fluorous phases, i.e. fluorous domains with at least one dimension in the nanometer range. Such fluorous nanophases are found in variously shaped micelles, Langmuir films, and bilayer membranes, as in vesicles, tubules and other molecular self-assemblies. Micron-size fluorous phases are present in diverse colloids that comprise liquid, solid and gaseous perfluorocarbons, such as in emulsions, microemulsions, multiple emulsions, microbubbles, gels and dispersions. Continuous or dispersed fluorous, hydrocarbonous and aqueous phases can be present simultaneously. Research on colloidal systems involving highly fluorinated components and destined for biomedical uses (injectable O 2 carriers, contrast agents, drug delivery systems and other devices) has generated a wealth of data. These data are analyzed here from the perspective of the formation, structure and behavior of fluorous nano- and microphases in colloidal systems. Fluorocarbons and fluorinated amphiphiles allow the formulation of an array of multicomponent, multiphase compartmented colloidal systems and nano-objects with various architectures, differential solubility and diffusibility characteristics, and other properties, and exclusion zones that have potential as microreservoirs, microreactors and templates useful for reaction, morphology and functionality control well beyond their initial biomedical purpose.