Surface modi®cation of silicon and silica in biological environment: an X-ray photoelectron spectroscopy study

The Earthʹs crust is primarily made of various silicate materials upon which we successfully dwell everyday. Numerous biomedical studies, however, have documented the toxicity of some of these materials when interacted with biological cells. It has become apparent that the surface chemistry of these silicates plays a key role in the cell pathogenesis, thus enhancing the value of the use of electron spectroscopy for chemical analysis (ESCA) or X-ray photoelectron spectroscopy (XPS) as a key method for analysis. Recent studies suggest that many common silicates, including silica itself, may not be innocuous to cell pathogenecity, thus suggesting their inclusion in these XPS studies. This paper presents a detailed study of the surface chemical modi®cation of silicon and silica when interacting with Ehrlich cells. XPS studies at selected stages of cell treatment reveal cell-induced alteration in the carbon, silicon, and oxygen of these silicon-based materials as well as changes in the carbon, iron, and nitrogen of the cell chemistry. Supporting results from the atomic absorption spectroscopy show similar changes. # 2001 Published by Elsevier Science B.V.