Effect of tannic acid on blood components and functions.

Tannic acid (TA) has become increasingly important as a biomaterial because of its ability to capture free radicals and form complexes with metal ions. Nevertheless, a systematic evaluation of the blood safety of TA has not been done. Therefore, we studied the effect of TA on erythrocyte morphology and hemolysis at different time points, and the fluorescence and circular dichroism (CD) spectroscopy of TA and fibrinogen. The blood coagulation time of TA was measured by the activated partial thromboplastin time (APTT), plasma prothrombin time (PT), and thrombelastogram (TEG) experiments. We found that higher concentrations of TA could lead to crinkling and hemolysis of erythrocytes, which may have been mediated by the hydrogen bond in TA. Spectroscopic results showed that TA influenced the structure and conformation of fibrinogen. Higher concentrations of TA could shorten the activated partial thromboplastin and plasma prothrombin times, and various concentrations of TA could affect the reaction time, clotting time, clot aggregation speed, and maximum clot strength of whole blood coagulation. These findings provide a basis for the design of TA molecules and the possible application of TA in biomedicine.