EFFECTS OF SURFACE-ACTIVE MEDIUM ADDITIVES ON INSECT-CELL SURFACE HYDROPHOBICITY RELATING TO CELL PROTECTION AGAINST BUBBLE DAMAGE

A number of medium additives such as Pluronic F68, methylcellulose, an d serum have been shown to decrease the adhesion of animal cells to ai r bubbles, thus reducing cell damage by the bubbles at rupture. The ef fect may be associated with the interactions between the additives and the cells. One possible mechanism is that the additives adsorb to the cell membrane through a hydrophobic interaction, resulting in decreas ed hydrophobicity of the cell surface. This consequently reduces cell adhesion to gas bubbles. To rest this hypothesis, we measured the hydr ophobicity (adhesion to a hydrocarbon) of two insect cell lines in the presence of medium additives including Pluronic F68, methylcellulose, polyethylene glycol (PEG), and fetal bovine serum. All these additive s except PEG caused substantial reduction in cell surface hydrophobici ty which was consistent with their effect of decreasing cell adhesion to gas bubbles. In addition, significant adsorption was detected for t he nonionic surfactants Pluronic and PEG to the insect cells. The find ings are very helpful for elucidating the mechanisms of animal cell pr otection by surface-active chemicals. (C) 1997 Elsevier Science Inc.