Nanoparticles (NPs) are ubiquitous in our environment and their presence inside our bodies is now established. In any biological medium, NPs get spontaneously covered by proteins that form the so-called protein corona. Depending on the corona composition, a NP will possess a specific "biological identity" conditioning its biodistribution and its potential toxicity. Despite being highly studied, many aspects of the protein adsorption mechanisms remain unknown. Here we particularly focused on the influence of two physicochemical characteristics, which had rarely been addressed : protein size and post-translational modifications. We studied the adsorption of hemoproteins on silica NPs, both of them having different sizes. Adsorption isotherms and calorimetry studies showed a relationship between the protein size and its affinity towards silica surfaces. Finer differences could also be observed by varying the SiNPs size. Additionally, structural analyses of adsorbed proteins were performed using circular dichroism and small-angle neutron scattering. The adsorption of hemoproteins, which are well-structured proteins, seems to have little effects on their structure. However, even though the quaternary structure is maintained, structural modifications can be seen. Using yeast protein extracts and synthetic peptides, the major role of arginine asymmetric dimethylation on proteins/SiNPs interaction could be established. The use of experimental and simulation techniques allowed us to understand the mechanism responsible for the high affinity of peptides having this peculiar methylation. As a whole, this work suggests that post-translational modifications can influence considerably the interactions between biomolecules and mineral surfaces.

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