Effects of long and short carboxylated or aminated multiwalled carbon nanotubes on blood coagulation.

In this work the effects of four different multiwalled carbon nanotubes (MWCNTs), including long carboxylated (L-COOH), short carboxylated (S-COOH), long aminated (L-NH(2)) and short aminated (S-NH(2)) ones, on the integrity of red blood cells, coagulation kinetics and activation of platelets were investigated with human whole blood. We found that the four MWCNTs induced different degrees of red blood cell damage as well as a mild level of platelet activation (10-25%). L-COOH and L-NH(2) induced a higher level of platelet activation than S-COOH and S-NH(2) respectively; meanwhile L-NH(2) caused marked reductions in platelet viability. The presence of the four MWCNTs led to earlier fibrin formation, L-NH(2) increased the clots hardness significantly, while L-COOH and S-NH(2) made the clots become softer. It was concluded that the four MWCNTs affected blood coagulation process and the clots mechanical properties; they also altered the integrity of the red blood cells and the viability of the platelets, as well as induced platelets activation. The effects of MWCNTs depended on the size and chemistry of the nanotubes and the type of cells they contacted.