• liquid-liquid extraction;
  • aqueous two-phase system;
  • bioparticles;
  • biomolecules

Upstream improvements have led to significant advances in the productivity of biomolecules and bioparticles. Today, downstream processes are the bottleneck in the production of some biopharmaceuticals, a change from previous years. Current purification platforms will reach their physical limits at some point, indicating the need for new approaches. This article reviews an alternative method to extract and purify biomolecules/bioparticles named aqueous two-phase system (ATPS). Biocompatibility and readiness to scale up are some of the ATPS characteristics. We also discuss some of ATPS applications in the biotechnology field. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1343–1353, 2013