Molecular interaction of fibrinogen with thermally modified titanium dioxide nanoparticles

The conformational changes of plasma fibrinogen structures in response to titanium dioxide nanoparticles are critical for determining their toxicity and their influence on blood coagulation. In this study, we combined micro differential scanning calorimetry (DSC), flow cytometry (FACS) and circular dichroism (CD) measurements to monitor the secondary structural changes of fibrinogen on thermally modified nanoparticles and subsequently the blood platelet activation corresponding to the adsorbed fibrinogen. Upon thermal modification, the crystalline phase of the titanium dioxide particles was transformed from anatase to rutile, and more negative charges were generated on them. The modified titanium dioxide particles then induced a loss in α-helical structure of fibrinogen with a decrease in transition enthalpy, which seems to be the highly sensitive structure affected by adsorption. Electrostatic interactions between the heated particles and the αC domains of fibrinogen led to a compact adsorption of proteins onto the particles and then a shielding of the platelet binding sites, which is regarded as an important mechanism to affect the hemocompatibility of the titanium dioxide nanoparticles.