Protein adsorption on silica nanoparticels and uptake by cells: an integrated approach

What cells “see” when are contacted with nanoparticles? The correct answer must consider the formation of an hybrid solid/protein interface, that could also result in the formation of a “corona” layer. In this study, as a first aspect we investigated quantitative and structural aspects of adsorption on silica nanoparticles (NPs), ca. 50 ± 2 nm in size, of a single model protein (BSA) and the serum protein pool. The capability of proteins to act as dispersion agent in BSA solution and culture media was observed (by DLS), as well as the formation of a thin (2–3 nm) corona around NPs (by TEM). Similar features were detected in TEM images of mesenchymal cells contacted with NPs, where a corona seemed to surround most part of NPs approaching cells membrane. Noticeably, the presence/absence of protein in the culture media was found to affect the rate of NPs uptake (monitored by fluorescence confocal microscopy) appeared significantly higher when proteins were absent.