The study of protein corona formation on nanoparticles (NPs) represents an actual main issue in colloidal, biomedical and toxicological sciences. However, little is known about the influence of polymer shells on the formation and time evolution of protein corona onto functionalized NPs. Therefore, silica-poly(ethylene glycol) core-shell nanohybrids (SNPs@PEG) with different polymer molecular weights (MW) were synthesized and exhaustively characterized. Bovine serum albumin (BSA) at different concentrations (0.1-6. wt%) was used as model protein to study protein corona formation and time evolution. For pristine SNPs and SNPs@PEG (MW = 350. g/mol), zeta potential at different incubation times show a dynamical evolution of the nanoparticle-protein corona. Oppositely, for SNPs@PEG with MW ≥ 2000. g/mol a significant suppression of corona formation and time evolution was observed. Furthermore, AFM investigations suggest a different orientation (side-chain or perpendicular) and penetration depth of BSA toward PEGylated surfaces depending on the polymer length which may explain differences in protein corona evolution. © 2012 Elsevier B.V.