Analysis of cell-to-bubble attachment in sparged bioreactions in the presence of cell-protecting additives

To investigate the mechanisms of cell protection provided by medium additives against animal cell injury in sparged bioreactions, the effect of various additives on the cell-to-bubble attachment process was analyzed using CHO cells in suspension. Cell-to-bubble attachment was examined using three experimental techniques: (1) cell-bubble induction time analysis (cell-to-bubble attachment times); (2) forming thin liquid films and observing the movement and location of cells in the thin films: and (3) foam flotation experiments. The induction times were measured for the various additives. Basing on the results of these cell-to-bubble attachment experiments, the cell-protecting additives were classified into three groups: (1) Pluronic F68, PVA, and Methocel (reduced cell-to-bubble attachment); (2) PEG and PVP (high or increased cell-to-bubble attachment); and (3) FBS (reduced cell attachment but slower drainage films).