Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments

Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca2+ ion balancing between intra-and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400 degrees C) on the intracellular Ca2+ ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca2+ concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca2+ ion balancing between extra-and intracellular environments and induced changes on Ca2+ ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca2+ ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing.