Titanium dioxide (TiO2) nanoparticles are widely used in food, cosmetics, biomedical implants, and pharmaceutical fields. Their effect on blood coagulation in human plasma and blood have been demonstrated. In this study, it is aimed to investigate whether the TiO2 particles of different shapes and sizes directly activate an intrinsic coagulation pathway protein factor XII (FXII). Two different TiO2 particles were morphologically characterized and prepared in physiological buffer solutions. The hydrodynamic radii and zeta potentials were measured using dynamic light scattering (DLS). The particles were incubated at 20, 10, 5 and 2.5 µg/ml (final concentrations) with 5 µg/ml FXII protein and enzymatic activity was measured with the help of a substrate of activated FXII (FXIIa). The enzyme activity was also measured in plasma in the presence and absence of corn trypsin inhibitor (CTI), a highly specific inhibitor of FXIIa. It has been found that FXII protein is activated in a dose-dependent manner by TiO2 particles, and this activation has been determined to occur independently of the particle hydrodynamic radius. However, it has been found that the zeta potential values of the particles in the buffer solution are directly related to the FXII enzymatic activity. It has been shown that TiO2 particles can activate the coagulation protein FXII based on surface charge distributions. Considering the possible effects of these materials on blood coagulation, zeta potential values should be considered when used in food and pharmaceutical production.
Key words: Titanium dioxide, particles, intrinsic coagulation pathway, factor XII
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