Protein coronas coating polymer-stabilized silver nanocolloids attenuate cytotoxicity with minor effects on antimicrobial performance

Silver nanoparticles are versatile platforms with a variety of applications within
the biomedical field. In this framework, their presence in biological media inevitably
leads to the interaction with proteins thus conducting to the formation of biomolecular
coronas. This feature alters the identity of the nanomaterial and may affect many
biological events. These considerations motivated the investigation of protein adsorption
onto the surface of polymer-stabilized AgNPs. The metallic colloids were coated by
polyethyleneimine (PEI), polyvinylpyrrolidone (PVP), and poly(2-vinyl pyridine)-bpoly(
ethylene oxide) (PEO-b-P2VP), and nanoparticle-protein interaction was probed by
UV-vis spectroscopy, light scattering, and sodium dodecyl sulphate-polyacrylamide gel
electrophoresis (SDS-PAGE). The data revealed a higher extent of protein adsorption at
the surface of AgNPs@ PVP whereas PEO-b-P2VP coating conducted to the least amount
of adsorbed proteins. The main component of the protein coronas was evidenced to be
bovine serum albumin (BSA), which is indeed the protein at the highest abundancy in the
model biological media used. We have further robustly demonstrated reduced
cytotoxicity of the silver colloids coated by biomolecular coronas as compared to the
pristine counterparts. Nevertheless, the protein coatings did not notably reduce the
antimicrobial performance of the polymer-stabilized AgNPs. Accordingly, although the
protein-repelling property is frequently targeted towards longer in vivo circulation of
nanoparticles, we herein underline that protein coatings, which are commonly treated as
artifacts to be avoided, may indeed enhance the biological performance of nanomaterials.
These findings are expected to be highly relevant in the design of polymer-stabilized
metallic colloids intended to be used in healthcare.