Polystyrene nanoparticles affecting blood coagulation.

The association of nanoparticles (NPs) with blood coagulation proteins may influence the natural balance between pro- and anticoagulant pathways. We investigated whether polystyrene NPs, when added to human plasma, affected the generation of thrombin in plasma. Amine-modified NPs were found to decrease the thrombin formation due to binding of factors VII and IX to the NPs, which resulted in depletion of the respective protein in solution. In contrast, carboxyl-modified NPs were able to act as a surface for activation of the intrinsic pathway of blood coagulation in plasma. These results highlight the influence of NPs on a biologically important pathway.