Probing the interaction of single walled carbon nanotubes within cell culture medium as a precursor to toxicity testing

Spectroscopic studies have been conducted in order to demonstrate and elucidate the interactions of HiPco((R)) single walled carbon nanotubes (SWCNT) with cell culture medium and its components, prepared both with and without foetal bovine serum. Upon addition of raw SWCNT to the medium a noticeable colour change was observed. UV/Vis absorption spectroscopy revealed a dramatic reduction in the absorption attributable to the phenol red, a pH indicator within the medium, without an associated change in pH. Reductions were also observed in absorbance features attributed to various components of the medium indicating an interaction with the SWCNT. Fluorescence spectroscopy also revealed reductions in emission features associated with the components of the medium giving further support to an interaction. Concentration dependent studies of the fluorescent emission of the various components of the media were modelled to show a differing degree of interaction between the SWCNT and the various components. Finally, notable differences were observed between the behaviour with and without serum. Raman spectroscopy gave no indication of differences between raw SWCNT and those deposited from the medium suspension indicating that no debundling of the SWCNT occurred. The results and their implications for toxicity and in vitro studies are discussed. (c) 2006 Elsevier Ltd. All rights reserved.