Cell Cultures: An Alternative in Biological Ion Microscopy

Most of the applications of ion microscopy to biological systems to date have involved the examination of thin tissue sections. Inherent in this approach has been the problem of redistribution of ions during sample preparation [1, 2]. An alternate approach which deserves exploration is the analysis of cell cultures. It has long been known that the study of cells growing and dividing in culture (in vitro) reveals many of the basic properties of cells, whose study is more difficult within the organisms. The use of tissue culture cells over thin sections in elemental distribution studies using ion microscopy provides several advantages. The cultured cells can be attached directly on the substrates typically used in SIMS analysis without showing any evidence of toxicity. This eliminates the need for tissue dissection before fixation, thereby limiting redistribution of diffusible elements (Na, K, Ca, etc.). The thickness of the cultured cells is less than 0.1 mm, so that their actual physiological and morphological states can be preserved relatively well by quick freezing [3].