Affinity extraction into carbon dioxide .1. Extraction of avidin using a biotin-functional fluoroether surfactant

Carbon dioxide is a naturally abundant, environmentally benign solvent whose use, like water, in a process is not regulated by either EPA or FDA. As such, CO2 would be an ideal medium to use in a liquid-liquid extraction process involving cell. culture-broth, in that contamination of the aqueous phase with residual organic would not be an issue. Unfortunately, amino acids and proteins are essentially insoluble in carbon dioxide. Further, alkyl-functional surfactants, which have been shown to allow extraction of proteins into conventional organic solvents, exhibit very poor or negligible solubility in CO2 at pressures below 50 MPa. Fortunately, recent work has shown that replacement of the alkyl hydrophobic portion of a surfactant with either fluorinated or siloxane-functional oligomers allows for high solubility in carbon dioxide and micelle formation, Consequently, biotinyl-fluoroether-functional surfactants have been generated and used to extract avidin into carbon dioxide. We extracted avidin into carbon dioxide via inverse and three-phase emulsions. We observed that the amount of avidin extracted via three-phase emulsion is twice as great as the protein extracted using an inverse emulsion.