The dispersion method does not affect the in vitro genotoxicity of multi-walled carbon nanotubes despite inducing surface alterations

with differentiated human monocytic (dTHP-1) cells. In addition, two dispersion methods (NanoGenoTox vs. high shear mixing) were utilised prior to exposures and in acellular experiments to assess the effects on MWCNT oxidative potential, aspect ratio and surface properties. These were characterized in chemico as well as by electron microscopy and Raman spectroscopy. Structural damage of NM-400 was observed following both dispersion approaches; Raman spectra highlighted greater oxidative transformation under probe sonication as opposed to high shear mixing. Despite the changes to the oxidative potential of the MWCNTs, no statistically significant genotoxicity was observed under the conditions applied. There was also no visible signs of cellular internaliation of NM-400 or NM-401 into either cell type under the test conditions, which may support the negative genotoxic response. Whilst these HARNs may have oxidative potential, cells have natural protective mechanisms for repairing transient DNA damage. Therefore, it is crucial to evaluate biological endpoints which measure fixed DNA damage to account for the impact of DNA repair mechanisms.