Nanostructure of the "protein-nanoparticle corona" an indicator of toxicity?

Nanoparticle-protein complexes comprising silica or cadmium sulfide nanoparticles with human proteins have been detected with high sensitivity at the air-water interface using X-ray and neutron reflectivity measurements and ellipsometry. For the interaction between β-casein and 8 nm silica particles the sensitivity of the reflectivity signal at the air-water interface has been shown by X-ray reflectometry to be pico-molar. This high sensitivity results from the nanoparticle-protein interaction which generates surface active complexes. The interaction between human serum albumin and cadmium sulfide nanoparticles has been detected using neutron reflectometry and tracked kinetically by ellipsometry. Here we have shown that lateral domains or aggregates in the surface monolayer change in size or dissipate over the course of several hours. The three methods of monitoring the protein-nanoparticle interaction during film evolution are discussed.