Spectroscopic investigations of human serum fibrinogen and magnetic iron (III) oxide nanoparticle interactions under normal and oxidative stress conditions

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The interactions of magnetic nanoparticles (MNP) with human serum fibrinogen and the effects of protein oxidation on binding affinity were investigated by UV-Vis, IR, fluorescence, and circular dichroism spectroscopy. Results indicated that MNP quench fibrinogen fluorescence mainly by a static quenching mechanism. The fluorescence quenching constants (Ksv) were determined as 1.60 x106 M-1 and 1.06 x106 M-1 at 300 K and 310 K respectively. The thermodynamic parameters of enthalpy change (ΔHo­­), entropy change (ΔSo­­), and free energy change (ΔGo) were – 23.37 kJ mol-1, 40.00 J.mol-1 and - 35.31 kJ. mol-1 (at 300 K) respectively. The formation of fibrinogen-MNP complex caused mild changes in the secondary structure of the protein. Metal catalyzed oxidation of fibrinogen resulted in significant changes in the secondary structure and adversely affected its binding affinity for MNP. After 4 hours of oxidation, the binding constant (Ka) of the fibrinogen-MNP interaction showed a four- fold decrease compared to that of unoxidized protein.


Advisor: Md Abul Fazal, Faculty Evaluator and co-advisor: Henry V. Jakubowski, Faculty Evaluator: Brian Johnson