Factors Affecting the Oxygen Tension around Cells Growing in Plastic Petri Dishes

Abstract

Anomalous observations on the survival of hamster cells irradiated while growing on polystyrene Petri dishes led to a detailed study of oxygen tension around the cells. It was found that polystyrene and other plastics held large quantities of oxygen in solution and released this slowly by diffusion. If the cells were covered by even a thin layer of liquid, this caused a build-up in oxygen concentration around the cells attached to the plastic surface. Of the several plastics tested for oxygen solubility and diffusion coefficient, only TPX and Mylar (or Melinex) seem to offer a hope that they may be suitable as a support for cells in anoxic experiments. Of these two, TPX is the better and is indeed the only one which allows 10⁻⁸ M [O₂] to be reached in a reasonable gassing time, assuming a liquid layer only 100 μ thick. The effect of the meniscus is discussed and the radiation-chemical binding of oxygen in both plastic and solution has been considered. It is pointed out that monitoring the effluent nitrogen for traces of oxygen is not an effective check on anoxic conditions around the cells.