THERMODYNAMIC APPROACH TO EXPLAIN CELL-ADHESION TO AIR-MEDIUM INTERFACES

Cell damage has been observed in suspension cell cultures with air sparging, especially in the absence of any protective additives. This damage is associated with cells adhering to bubbles, and it has been shown that if this adhesion is prevented, cell damage is prevented. This article presents a thermodynamic approach for predicting cell adhesion at the air-medium interface. With this relationship it can be shown that cell-gas adhesion can be prevented by lowering the surface tension of the liquid growth medium through the addition of surface-active protective additives. The thermodynamic relationship describes the change in free energy as a function of the interfacial tensions between the (i) gas and liquid phases, (ii) gas and cell phases, and (iii) liquid and cell phases. Experimental data, along with theoretical and empirical equations, are used to quantify the changes in free energy that predict the process of cell-gas adhesion. The thermodynamic model is nonspecific in nature and, consequently, results are equally valid for all types of cells. (C) 1995 John Wiley & Sons, Inc.