Elution profile from periodic counter current capture step as an on-line monitoring and control tool for perfusion bioreactors

Conference Dates

October 6-10, 2019


Current trends in bioprocessing move towards the implementation of more on-line sensors such as Raman spectroscopy for titer monitoring in perfusion bioreactors. However, process performance data from one downstream unit operation can also be used to monitor and control the unit operation directly upstream. Despite several authors demonstrated a successful integration of continuous up-and downstream processes little attempts have been made to leverage the information derived from downstream processing as a real time feedback loop for upstream processing. We have developed a simple and robust approach in which protein A periodic counter current chromatography (PCCC) can function as an on-line monitoring tool for protein titer in continuous upstream fermentations. For a proof of concept, we exploit the fact that performance and binding capacities of state of the art protein A chromatography material do not significantly decrease throughout hundreds of cycles. Therefore, it is possible to predict the concentration of antibodies in the feed material from the elution pool and the volume loaded onto the column. We use the breakthrough curve during the interconnected phase of the PCCC, which is key for this approach. In the interconnected phase, the first column was loaded to 80% breakthrough, and the breakthrough curve modelled for a number of different concentrations in the feed material. Using the breakthrough curve, the time of the breakthrough can be modelled against the increase of product present in the feed stream, allowing the prediction of the concentration of antibody in the perfusion fermentation. This information feedback loop through the integration of PCCC and fermentation into effectively one single unit operation makes the titer determination in the fermentation obsolete, using the PCCC effectively as online monitoring tool itself. Future work after this proof of concept will include the prediction of protein A binding capacities through the lifetime of the resin and determination of accuracy and quantification limits the of interconnected units.

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