DEVELOPMENT OF AN IN VITRO ELECTROCHEMICAL TOXICITY ASSAY AND ITS APPLICATION TO NANOTOXICOLOGY.

 

Bryce J. Marquis1 and Christy L. Haynes2

 

1)       Now at National Institute of Standards and Technology, Biochemical Science Division, Gaithersburg, MD

2)        University of Minnesota, Minneapolis, MN

 

With nanotechnology’s increasing prevalence in consumer products, there is growing demand for toxicological information regarding these emerging technologies. Current popular cytotoxicology methods feature viability assays conducted on homogenous cell culture systems. These studies reveal little insight into how cell function changes after nanoparticle exposure.  In this work, a cutting-edge analytical chemistry technique, single-cell amperometry, is used to assess changes in an important cellular function, exocytosis, when exposed to potential toxicants in vitro. This work outlines the development and characterization of a mast cell / fibroblast co-culture model with single-cell amperometry, its use in assessing the effects of known toxicants, and its application to nanotoxicological studies featuring noble metal nanomaterials. Single-cell amperometry studies are compared to bulk assays including both bulk viability and exocytosis assays. In the nanotoxicological work, a series of nanoparticle syntheses were conducted yield gold and silver nanoparticles with varied size and surface functionality. ICP-OES measurements find significant cellular uptake for co-cultured cells exposed to gold and silver nanomaterials. TEM evaluation of exposed cells finds the highest degree of nanoparticle localization within secretory organelles. Correlated single-cell amperometric measurements demonstrate that nanoparticle exposure results in impaired chemical messenger secretion. These functional studies contrast results from traditional viability assays, which often indicated little changes in cellular function with nanoparticle exposure.  These studies are the first of their kind, demonstrating the potential of single-cell amperometry measurements as a technique for assessing the effects of both molecular and nano-scale toxicants on this critical cellular function.