Effects of Oxidation on Protein-Nanoparticle Interactions

Aims: Upon entrance into the blood stream most nanoparticles bind to an array of proteins forming a “protein corona”. Fibrinogen is the second most abundant blood protein and has been reported to bind to a variety of nanoparticles including metal oxides, polymeric nanoparticles and carbon nanotubes.
Study Design: Study the effects of oxidation on the binding interactions between human serum fibrinogen and magnetic iron (III) oxide nanoparticles.
Place and Duration of Study: Department of Chemistry, College of St. Benedict, 37 South College Avenue, St. Joseph, MN 56374, U.S.A., between June 2011 and May 2012.
Methodology: Spectroscopic techniques (UV-Vis, IR, fluorescence, and circular dichroism) were used to study the binding interactions of magnetic nanoparticles with human serum fibrinogen and the effects of protein oxidation on its binding affinity.
Results: Magnetic nanoparticles (MNP) formed stable complex with fibrinogen under physiological conditions. The binding constants (Ka) were determined as 1.91 (± 0.14) x106 M-1 and 1.06 (± 0.09) x106 M-1 at 300 K and 310 K respectively. The secondary structure of the protein was slightly affected by the formation of fibrinogen-MNP complex. When the protein was oxidized with metal catalyzed oxidation (MCO) system, significant changes in the protein structure was detected leading to decreased binding affinity for MNP.
Conclusion: Metal catalyzed oxidation of fibrinogen significantly affects its binding interactions with magnetic iron (III) oxide nanoparticles.