Root Mean Square Deviation calculated from molecular dynamics trajectories.

<p>AP group (left) and NAP group (right).</p

Representative structures of proteins belonging to AP and NAP groups.

<p>Left: Rps0a for the AP group. Right: Cpr1 of the NAP group. The secondary structures of the protein are displayed in cartoon mode. The aromatic residues are shown in yellow in line mode and the interactions between backbone carbon atoms of the aromatic residues are displayed in red to show the aromatic clusters in both groups.</p

Cumulative distribution for selected parameters.

<p>The AP group is represented by a solid line and the NAP group by a dotted line. The parameters presented are aromatic amino acids (Phe + Tyr + Trp + His), polar amino acids, hydrophobic amino acids, Arginine, Glutamate and Lysine.</p

Characterization of silica nanoparticles used in the study.

<p>Transmission electron microscopy images of silica NPs: (A), small aggregated particles and (B), single large particle. (C) Small angle neutron scattering profiles of silica NPs; experimental data (■) and fitting by a particle size distribution (gray line). (D) adsorption isotherm of yeast proteins on silica NPs in PBS buffer; experimental data (□) and fitting by the Langmuir model (black line).</p

RNA-binding proteins are a major target of silica nanoparticles in cell extracts

<p>Upon contact with biological fluids, nanoparticles (NPs) are readily coated by cellular compounds, particularly proteins, which are determining factors for the localization and toxicity of NPs in the organism. Here, we improved a methodological approach to identify proteins that adsorb on silica NPs with high affinity. Using large-scale proteomics and mixtures of soluble proteins prepared either from yeast cells or from alveolar human cells, we observed that proteins with large unstructured region(s) are more prone to bind on silica NPs. These disordered regions provide flexibility to proteins, a property that promotes their adsorption. The statistical analyses also pointed to a marked overrepresentation of RNA-binding proteins (RBPs) and of translation initiation factors among the adsorbed proteins. We propose that silica surfaces, which are mainly composed of Si–O⁻ and Si–OH groups, mimic ribose-phosphate molecules (rich in –O⁻ and –OH) and trap the proteins able to interact with ribose-phosphate containing molecules. Finally, using an <i>in vitro</i> assay, we showed that the sequestration of translation initiation factors by silica NPs results in an inhibition of the <i>in vitro</i> translational activity. This result demonstrates that characterizing the protein corona of various NPs would be a relevant approach to predict their potential toxicological effects.</p