In vitro toxicity assessment of carbon nanomaterial dispersions

Background: Carbon nanotubes (CNT) may represent a potential health risk, because there are possible adsorbtion pathways through skin and lung. In the blood they can agglomerate with lipophilic serum proteins and get in touch with many cell types and tissues, if protein coated CNT agglomerates can penetrate endothelium. By their high surface as well as their residual concentration at catalyst materials these possible bioactive and biopersistent particles have the potential to harm cells by releasing inflammation reactions, oxidative stress and even necrosis and apoptosis. Aim: For testing the biocompatibility according to DIN ISO 10993-5 in BMBF-supported ""TRACER"" (Toxicology and health risk assessment of carbon nanomaterials), we examine different kinds of dispersive and converted CNT materials for possible cytotoxic characteristics. Methods: Defined CNT-dispersions depending on particle size and catalyst materials were characterized with optical density and particle size distribution. According to reference material in vitro biocompatibility was measured with cell proliferation assays (WST-1), reactive oxygen species detection (ROS) and activation of immune cells (FACS) with relevant primary cells, cell lines and 3D-testsystems (skin, trachea and vascularized matrix) after incubation with CNT. Results: Investigations exhibit a changed proliferation attitude to CNT incubation concerning CNT kind, size distribution and residual concentrations of catalyst material. Although CNT exhibit proliferation in dose-dependent way, acute toxicity compared to asbestos or Carbon Black could not be observe. Outlook: Cytotoxic assessment of CNT is facilitated with a combination of exact material characterisation and in vitro toxicological tests. After this, health risks could be estimated and guidelines for employment protection recommended.