Abstract

The interaction of nanoparticles with body fluids may induce conformational changes in the proteins present in the medium. Such interactions could induce functional loss or important modifications in some proteins, and trigger cellular events induced by the NP-protein moiety. As metal oxide nanoparticles are widely used for various applications, the interaction of four different metal oxide nanoparticles (ZnO, TiO2, CeO2 and Al2O3) with three of the main protein fractions from human plasma (albumin, fibrinogen and globulins) was characterized by fluorescence and Fourier-transform infrared (FTIR) spectroscopy. The pattern of nanoparticle-protein interaction was shown to vary from a strong interaction with ZnO nanoparticles, which induced a decrease in the thermal stability of fibrinogen and albumin at a low temperature, and interferes with the clotting of fibrinogen, to a slight or null interaction with Al2O3 nanoparticles at physiological pH. The influence of pH was also characterized for albumin, with the interaction showing an important dependence on the surface charge of the nanoparticles. 

Metal oxide nanoparticles induced conformational changes in the secondary structure of albumin, principally the transformation of a-helices into ß-sheet structures. This interaction, with the exception of Al2O3 nanoparticles at basic pH, could take place in domain II of the protein, formed mainly by hydrophobic and positive residues.