Surface energetics to assess biomass attachment onto immobilized metal-ion chromatography adsorbents in expanded beds |
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Authors: | Rami Reddy Vennapusa Muhammad Aasim Rosa Cabrera Marcelo Fernandez-Lahore |
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Institution: | 1. Downstream Processing Laboratory, Jacobs University Bremen gGmbH, Campus Ring 1, D-28759, Bremen, Germany
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Abstract: | Cell-to-support interaction and cell-to-cell agglomeration phenomena have been studied in a model system composed of intact
yeast cells and Chelating-Streamline™ adsorbents. Biomass components and beaded adsorbents were mainly characterized by contact
angle determinations with three diagnostic liquids. Complementarily, zeta potential measurements were performed. These experimental
values were employed to calculate free energy of interaction versus distance profiles in aqueous media. The effect of immobilized
metal-ion type and buffer pH on the interaction energy was evaluated. Calculations indicated that moderate interaction between
cell particles and adsorbent beads can develop due to the presence of Cu2+ ions onto the solid phase. The strength of interaction increased with buffer pH, within the range 6.0 to 8.3 e.g. secondary energy pockets increased from |15| to |60| kT. Cell-to-cell secondary energy minimum was ≥ |14| kT showing low-to-moderate tendencies to aggregate, particularly at pH ≥ 8. Extended DLVO predictions were generally confirmed
by biomass deposition experiments. However, an exception was found when working with immobilized Cu2+ at pH 8 since yeast cells were able to sequestrate such immobilized ions. Therefore, lower-than-expected values for the depositions
coefficient (α) were observed. Understanding biomass attachment onto Chelating supports can help in better design and operate
expanded bed adsorption of bioproducts. |
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