Novel affinity separations based on perfluorocarbon emulsions: Development of a perfluorocarbon emulsion reactor for continuous affinity separations and its application in the purification of human serum albumin from blood plasma

Abstract

Perfluorocarbon affinity emulsions are generated by the homogenisation of a perfluorocarbon oil with a polymeric fluorosurfactant previously derivatised with an affinity ligand and subsequently cross-linked in situ. This procedure gives rise to a novel liquid affinity adsorbent that can be used for continuous protein purification. Discrete emulsion droplets were found to be unstable when pumped for prolonged periods; however, when flocculated, the emulsion floccules with diameters of around 125 μm, were very stable and sedimented faster. A four-stage reactor unit (perfluorocarbon emulsion reactor for continuous affinity separations, PERCAS) was designed and constructed to carry out continuous separations, and exploited the unusual properties of the adsorbent, i.e. liquid nature and high density. Each of the four stages of PERCAS consisted of a mixing tank, for contacting between emulsion phase and aqueous phase, adjacent to a settling tank for the subsequent separation of emulsion from the aqueous phase. Using PERCAS adsorption, washing, elution and re-equilibration of the emulsion could be carried out continuously with emulsion recycle. Using single-component adsorption of human serum albumin to a perfluorocarbon affinity emulsion derivatised with the triazine dye C.I. Reactive Blue 2, PERCAS was optimised with respect to flow-rates and input concentrations. The work was then extended to the continuous purification of essentially homogeneous human serum albumin from blood plasma.