WATER IN CARBON-DIOXIDE MICROEMULSIONS - AN ENVIRONMENT FOR HYDROPHILES INCLUDING PROTEINS

Carbon dioxide in the liquid and supercritical fluid states is useful as a replacement for toxic organic solvents. However, nonvolatile hydr ophilic substances such as proteins, ions, and most catalysts are inso luble. This limitation was overcome by the formation of aqueous microe mulsion droplets in a carbon dioxide-continuous phase with a nontoxic ammonium carboxylate perfluoropolyether surfactant. Several spectrosco pic techniques consistently indicated that the properties of the dropl ets approach those of bulk water. The protein bovine serum albumin (BS A) with a molecular weight of 67,000 is soluble in this microemulsion and experiences an environment similar to that of native BSA in buffer .