abstract
The advent of biopharmaceuticals in modern medicine has brought enormous benefi ts to treat chronic and life-threatening diseases while improving the well-being of humans. Proteins (including antibodies) represent a large fraction of the biopharmaceuticals market, but are still amongst the costliest options due to the lack of cost-eff ective purifi cation techniques. The most relevant strategies in the downstream processing of protein-based biopharmaceuticals are the highly selective nature of chromatographic techniques, which however, present some drawbacks including the diffi culty to apply in large scale due to batch processing, large scale pressure drops, 1 low chemical and proteolytic stability, and high cost. 2 To overcome such limitations, alternative downstream processes have been proposed, such as aqueous two-phase systems (ATPS). These systems were initially proposed by Albertsson in the mid 1950s as an alternative to traditional liquid-liquid extraction techniques, 3 consisting of two immiscible aqueous-rich phases that separate above given concentrations, being one aqueous phase enriched in one of the solutes while in the other phase the second component prevails. 4 An overview of the application of ATPS for the purifi cation of proteins is represented in Figure 1, being additionally illustrated is a typical ATPS ternary phase diagram in an orthogonal representation, in which the water concentration is not shown (pure water becomes the origin of the orthogonal axes, corresponding to the amount required to reach 100 wt% in a given mixture composition). 4 In comparison with other extraction techniques, ATPS display several advantages, spanning from their environmentaly friendly and biocompatible character, low cost, continuous operation and easiness Figure 1. Schematic representation of protein purii cation using an ATPS and of an orthogonal ternary phase diagram for a hypothetical system.
authors
Castro, L. S.; Pereira, P.; Freire, M. G.; Pedro, A. Q.
our authors
