Visualization of Carbon Nanoparticles Within Cells and Implications for Toxicity

Abstract

Carbon nanostructures (CNS), such as C-60, single-walled nanotubes (SWNTs) exhibit extraordinary properties and are one of the most commercially relevant class of NS. CNS have already found uses in high-performance sports equipment (nanotubes) and face cream (C-60), whilst potential applications include optical and electronic materials and superconductors. Following the huge growth in these nanotechnology-related industries, significant concerns have arisen about their potential toxicity and impact on the environment. A lack in understanding of the interaction of such small structures with cellular material has resulted in concerns over their impact on human health. The potential toxicity of CNS and safety to human health requires an understanding of their interaction with cells and this in turn relies on the measurement of the pathways by which they enter the cell, their spatial distribution within and whether the CNS are transformed by the action of the cell; visualization of intracellular CNS is therefore imperative. However visualizing unlabelled CNS within cells is demanding because it is difficult to distinguish CNS from carbon-rich organelles given their similarity in composition and dimensions. In particular, the challenge lies in translating analytical imaging tools developed for inorganic systems to organic systems. This chapter describes how the state-of-the-art transmission electron microscopy (TEM) techniques, such as low-loss energy-filtered TEM (EFTEM) can be employed to differentiate between unlabelled C-60, SWNTs and the cell. Further, we demonstrate how these techniques can be used to trace the uptake of CNS into the cell and to assess their localized effects on cell structure.