China Bio Exchange

This international collaboration was inspired by Dr. Fernandez-Lahore and Dr. Dong-Qiang Lin's enthusiasm for downstream bioprocessing and the impressive advantages it brings to a number of food-processing industries.

The prestigious Robert Bosch Foundation awarded the two prominent academics a research grant in 2009. This funding has enabled Dr. Fernandez-Lahore, Dr. Don-Qian Lin and their groups to focus on the development of cost-efficient ways to implement downstream bioprocessing in mainstream biological manufacturing.

Partners

Prof. Dr. Marcelo Fernández Lahore is the Director of the Downstream Bioprocessing Laboratory at Jacobs University Bremen, Germany. He and his research group work on the chromatographic characterization of novel materials for chromatography.

These investigations also include detailed study of the separation behaviour of (bio) products and contaminants during processing. Dr. Fernández Lahore’s group has implemented a routine based on modern proteomic tools. In essence, a complex biological sample is subjected to chromatography under standard conditions, fractions are collected, and further analysed by two-dimentional gel electrophoresis and mass spectrometry.

As a result, general tendencies are observed within the population of the separand entities and contaminants are identified. In the particular case of mixed-mode ligands, interaction effects with soluble proteins are complex and thus, “process-proteomics” is able to generate a much better understanding and predictability of the processes involved.

Prof. Dr. Dong-Qiang Lin’s lab at Zhejiang University in China has developed multi-functional ligands for mixed-mode chromatography. Mixed-mode chromatography is a new kind of chromatographic technology for bioseparation.

Mixed-mode ligands have multiform binding functions, commonly combining hydrophobic and electrostatic interactions. The charged groups of the ligand at low ionic strength perform the ion-exchange adsorption of target protein, as the ionic strength increases the aromatic ring of the ligand allows the hydrophobic interaction to target for salt-tolerant adsorption.

As a result, high binding capacities can usually be achieved at the moderate conductivities (10-30 mS/cm) without additional dilution steps in advance. The desorption of mixed-mode adsorbent can be achieved due to the electrostatic charge repulsion, and is often accomplished by changing the pH of the mobile phase.

In general, this novel technique is especially appropriate for primary capture of target protein from moderate ionic strength feedstock without the need of dilution or other additives, which certainly improves the process efficiency and reduces the cost of primary recovery in the downstream process.

The key point is to design rationally the molecular structure of mixed-mode ligands. Currently, Prof. Lin is developing novel mixed-mode ligands for effective antibody purification, which combines the high adsorption capacity of hydrophobic groups, high selectivity of thiophilic groups and the efficient elution due to electrostatic repulsion. Several kinds of potential mixed-mode ligands have been found in the lab and coupled onto the cellulose-based adsorbents, which showed good properties for selective adsorption of antibodies.

In addition, computer-aided molecular simulation methods are used to better understand the interactions between antibody and mixed-mode ligand, while subsequently optimizing the functional groups of mixed-mode ligands for enhancing the separation efficiency of antibody purification.

The results strongly indicate that mixed-mode adsorption is a potential effective-and-economic substitute for expensive Protein-A affinity separation for antibody production. In a recent visit to Jacobs University, Prof. Lin has started to utilize computational tools (docking studies) to simulate and obtain quantitative information on mixed-mode ligand interaction with model proteins. These studies can be continued in the near future.

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