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BioMed Research International
Volume 2013, Article ID 564804, 13 pages
Research Article

Suitability of Cell-Based Label-Free Detection for Cytotoxicity Screening of Carbon Nanotubes

1Center for Medical Research, Medical University of Graz, 8010 Graz, Austria
2Department of Pharmaceutical Technology, Institute of Pharmaceutical Sciences, Karl-Franzens-University of Graz, 8010 Graz, Austria

Received 27 May 2013; Revised 31 October 2013; Accepted 1 November 2013

Academic Editor: M. Piacentini

Copyright © 2013 Claudia Meindl et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cytotoxicity testing of nanoparticles (NPs) by conventional screening assays is often complicated by interference. Carbon nanotubes (CNTs) are particularly difficult to assess. To test the suitability of cell-based label-free techniques for this application, a panel of CNTs with different diameters and surface functionalizations was assessed by impedance-based technique (xCELLigence RTCA) and automated microscopy (Cell-IQ) compared to formazan bioreduction (MTS assay). For validation of the label-free systems different concentrations of ethanol and of amine (AMI) polystyrene NPs were used. CNTs were evaluated in various cell lines, but only endothelial EAhy926 cells and L929 and V79 fibroblasts could be evaluated in all systems. Polystyrene particles obtained similar results in all assays. All systems identified thin (<8 nm) CNTs as more cytotoxic than thick (>20 nm) CNTs, but detection by xCELLigence system was less sensitive to CNT-induced cytotoxicity. Despite advantages, such as continuous monitoring and more detailed analysis of cytotoxic effects, label-free techniques cannot be generally recommended for cytotoxicity screening of NPs.