Use of Ionic Liquids as Cosurfactants in Mixed Aqueous Micellar Two-Phase Systems to Improve the Simultaneous Separation of Immunoglobulin G and Human Serum Albumin from Expired Human Plasma

A large fraction of unused clinical transfusion plasma is nowadays discarded. Nevertheless, some proteins, including serum albumin, immunoglobulins, and clot factors, are still viable for use in diagnosis or research. However, lasma is a complex matrix, requiring multiple steps and time-consuming methods for the isolation of proteins. In this work, aqueous micellar two-phase systems (AMTPS) composed of nonionic surfactants (Triton X-114 or Tergitol 15-S-7) were investigated to simultaneously separate immunoglobulin G (IgG) and human serum albumin (HSA) from human expired plasma. A factorial planning was applied to the nonionic surfactant and plasma concentrations to enhance the systems separation performance. After identifying the best conditions with AMTPS formed by nonionic surfactants, mixed AMTPS formed by Tergitol 15-S-7 and various surface-active ionic liquids (SAILs) acting as cosurfactants were additionally investigated to tailor the proteins partition between the two phases. The mixed AMTPS composed of Tergitol 15-S-7 as the nonionic surfactant and tributyltetradecylphosphonium chloride as the cosurfactant at pH 8.0 improved the simultaneous separation of both proteins to the opposite phases. IgG purification of 1.14-fold in the surfactant-poor phase and HSA purification of 1.36-fold in the surfactant-rich phase were obtained. Method reproducibility was investigated using additional samples of human serum and plasma and serum mixtures. Although improvements in the purification factor of each protein are still a future goal, mixed AMTPS comprising nonionic surfactants and SAILs as cosurfactants may be considered as novel platforms to be used in the simultaneous separation of value-added compounds from complex and natural matrices.