Enhanced extraction of proteins using cholinium-based ionic liquids as phase-forming components of aqueous biphasic systems


Aqueous biphasic systems (ABS) composed of ionic liquids (ILs) are promising platforms for the extraction and purification of proteins. In this work, a series of alternative and biocompatible ABS composed of cholinium-based ILs and polypropylene glycol were investigated. The respective ternary phase diagrams, tie-lines, tie-line lengths and critical points were determined at 25 degrees C. The extraction performance of these systems for commercial bovine serum albumin (BSA) was then evaluated. The stability of BSA at the IL-rich phase was ascertained by size exclusion high-performance liquid chromatography and Fourier transform infrared spectroscopy. Appropriate ILs lead to the complete extraction of BSA for the IL-rich phase, in a single step, while maintaining the protein's native conformation. Furthermore, to evaluate the performance of these systems when applied to real matrices, the extraction of BSA from bovine serum was additionally carried out, revealing that the complete extraction of BSA was maintained and achieved in a single step. The remarkable extraction efficiencies obtained are far superior to those observed with typical polymer-based ABS. Therefore, the proposed ABS may be envisaged as a more effective and biocompatible approach for the separation and purification of other value-added proteins.



subject category

Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology


Quental, MV; Caban, M; Pereira, MM; Stepnowski, P; Coutinho, JAP; Freire, MG

our authors


This work was financed by national funding from FCT Fundacao para a Ciencia e a Tecnologia, through the project Pest-C/CTM/LA0011/2013. M. M. Pereira acknowledges the PhD grant (2740-13-3) and financial support from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Capes. M. Caban acknowledges the funding of COST Action CM1206 'EXIL - Exchange on Ionic Liquids. Mara G. Freire acknowledges the European Research Council (ERC) for the Starting Grant ECR-2013-StG-337753.

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