ISBN 9783843909815

978-3-8439-0981-5, Reihe Verfahrenstechnik

Joachim Samatou
Modelling and Simulation of Antibody Purification by Aqueous Two-Phase Extraction

196 Seiten, Dissertation Technische Universität Dortmund (2012), Softcover, A5

Zusammenfassung / Abstract

In this work, a computer aided approach for protein purification using multi-stage ATP extraction is presented. The approach was tested using immunoglobulin G (IgG) antibody purification from a fermentation broth as an example. This extraction was investigated for two aqueous two-phase systems (ATPSs). The polyethylene glycol-phosphate system containing NaCl and the polyethylene glycol-dextran system containing triethylene glycol functionalised with glutaric acid (TEG-GA). NaCl and TEG-GA are entrainers that improve the IgG partitioning into the PEG phase for both systems. The distribution of these entrainers into both phases is an important aspect for designing a multistage extraction unit as a sufficient concentration must be present in each stage. Therefore, the liquid-liquid equilibria of both ATPSs were experimentally investigated in the presence of the entrainers. In these investigations, the entrainer distribution and influence on the volume ratio were quantified.

An equilibrium stage model with modular structure was developed and used to conceptualise a process for the antibody purification. For the phase-forming components, the Virial Equation with Relative Surface Fractions model was used, whereas various correlations were developed for the proteins. One advantage of this model structure is that the investigated ATPSs can be used to purify many proteins; however, the protein partitioning has to be measured again for each protein.

Simulation studies of multistage arrangements were performed for both systems. The model for the PEG-phosphate ATPS was successfully validated using literature experiments performed with a mixer-settler battery. The deviations between the model and pilot plant experiments proved to be less than 10% with respect to the product recovery and purity. Finally, this model was used to simulate a downstream process based on three extraction steps and predicted a process yield of 95% and a product purity of 99%.