Interactions of CoFe2O4 Nanocrystals with Bovine Serum Albumin and Hemoglobin: Adsorption, Aggregation and Protein Conformational Changes

Cobalt ferrite (CoFe2O4) nanocrystals (approximately 10 nm) were prepared by hydrothermal method and their interactions with Bovine Serum Albumin (BSA) and bovine hemoglobin were investigated by Zeta potential, Dynamic Light Scattering (DLS) and FTIR Spectroscopy techniques. Results show that nanocrystal-hemoglobin adsorption correlates to electrostatic attractive/repulsive interaction, whereas BSA does not follow this scheme. The corresponding adsorption capacity of BSA and hemoglobin reaches a maximum value of 237.9 mg.g(-1) and 256.9 mg.g(-1) at pH value of 5.5 and 7.0, respectively. DLS measurements indicate that protein adsorption have led to nanocrystal-protein aggregates formation. Comparing to the hydrodynamic size of bare nanocrystals (51 nm), that for BSA and hemoglobin increases to 472 nm and 114 nm respectively upon protein adsorption. The interaction with nanocrystal also induces protein conformation changes. The amide I band in IR spectrum shifts 4 cm(-1) and 6 cm(-1), respectively, to lower wavenumbers in the case of BSA and hemoglobin.