Single Cell Array Based Assay for in Vitro Genotoxicity Study of Nanomaterials

This paper describes the use of a single cell array based assay for genotoxicity study of nanomaterials using normal human fetal fibroblast cells obtained from two-dimensional (2D) monolayer cultures and three-dimensional (3D) microtissue. After being exposed to a suspension of nanomaterials, cells are attached onto microfabricated patches with proper modification through electrostatic attraction and embedded in hydrogel. The damaged DNAs diffuse in gel matrix and form observable halo structures, where the level of DNA damage is quantified from the dimensions of core and halo. A concentration dependent genotoxicity has been found in nanomaterials. Compared to the traditional cytotoxicity (live/dead) assay, the genotoxicity results from the single cell array based assay are more robust and sensitive at the same exposure concentration, indicating that nanomaterials cause significant DNA damage without detectable cytotoxicity. In addition, cells from 3D microtissues are less damaged than 2D culture due to different cell microenvironments.