Christian Kress


Predicting phase behaviour of aqueous-protein solutions


Area: downstream processing
Project Start: 1.05.2013
Supervisor(s): Prof. Dr. Gabriele Sadowski
University: Dortmund



The development of industrial scale bioprocesses has come into scientific and industrial interest over the last decades. Especially in the red and white biotechnology process costs are often dominated by up to 80% by the downstream processing due to state of the art cost-intense chromatographic purification procedures [1]. Aqueous two-phase systems are a promising alternative providing a selective purification of biomaterials in a biocompatible environment. Within this work, a physical properties based model will be developed to allow for the prediction of the thermodynamic behavior of biological macromolecules in complex systems.


Biothermodynamics offers several tools to account for physical and thermodynamic properties of complex reaction mixtures. Thus, it can serve as an innovative approach for the characterization of these systems. Promising and fast measures accounting for complex interactions of biological macromolecules are the surface hydrophobicity and osmotic virial coefficients. Herein, the second osmotic virial coefficient B22 characterizes the self-interaction between the biological macromolecules in solution and the cross virial coefficient B23 describes the interaction between different solutes. The main advantage of this approach is the consideration of different influence factors such as pH, temperature, solvent, solutes and solute concentration within one measurement. It is the aim of this project to use these measurements (second osmotic virial coefficient and hydrophobicity) to develop a physical property based approach to account for important key factors in the downstream processing development. These key factors include but are not limited to the solubility, crystallization behavior and partitioning of biological macromolecules. For this purpose different biological macromolecules like amino acids, small and large proteins will be considered. In order to investigate the possibilities to predict the partition behavior, the second osmotic virial coefficient and the surface hydrophobicity will be measured in different solvent systems. On the basis of this data a thermodynamic model will be developed to predict the thermodynamic behavior of biological macromolecules in complex systems. Based on the results of this work, a simplified downstream processing development compared to conventional approaches will be enabled.

[1] A. M. Azevedo, P. A. J. Rosa, and M. R. Aires-Barros: "Chromatography-free recovery of biopharmaceuticals through aqueous two-phase processing" Trends in Biotechnology, vol 27, pp. 240–247, 2009


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