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

Claudia Meindl,Markus Absenger,Eleonore Fröhlich,Eva Roblegg

doi:10.1155/2013/564804

Claudia Meindl, Markus Absenger + Show 2 more

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https://doi.org/10.1155/2013/564804

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Abstract

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.

Highlights

Nanoparticles (NPs) are used in a variety of industrial, consumer, and medical products
These Carbon nanotubes (CNTs) are synthesized by catalytic chemical vapour deposition and are purified with dilute nitric acid
This study shows that cytotoxicity of CNTs can be assessed by formazan bioreduction (MTS assay), impedance measurements, and automatic microscopy (Cell-IQ Analyzer) with different sensitivity

Summary

Introduction

Nanoparticles (NPs) are used in a variety of industrial, consumer, and medical products. Conventional CSAs are based on the quantification of enzyme activity, protein content, DNA content, and organelle function. These detections are based on colorimetric, fluorometric, luminescent, and, less frequently, radiometric measurements. Interference with assays appears to be likely when the protocol affords lysis of the cells [15]. In this situation, testing by label-free techniques could be advantageous. Testing in the absence of dyes might be important because influence of dyes on cellular function has been reported. 2󸀠,7󸀠-Bis(2carboxyethyl)-5-(and 6)-carboxyfluorescein (BCECF-AM), used for measurement of intracellular pH, and rhodamine 6G, used for labelling of mitochondria, can dose-dependently block migration in phagocytes [16]

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