Role of surface functionalization and biomolecule structure on protein corona adsorption and conformation onto anisotropic metallic nanoparticles

In the biological milieu, nanoparticles (NPs) interact with different biomolecules, particularly proteins, leading to the formation of an interfacial corona, which gives rise to a new biological identity affecting NP biodistribution, cytotoxicity and biological fate. The surface coating of NPs plays a key role in regulating such biocorona formation and composition. We here investigated the interactions between bovine serum albumin (BSA) and bovine fibrinogen (FIB) with gold nanorods (Au NRs) bearing different surface coatings (cetyltrimethylammonium bromide, CTAB, and carboxylic acid and amine-terminated polyethylene glycols (PEGs). It was revealed that CTAB-coated NPs interact with both proteins with high affinity (ca. 108-109 M-1) whereas for PEG ones the extent of protein binding decreases thanks to the stealth properties of PEG, but a protein corona is still formed, with binding affinities between 104-106 M-1. In addition, present results indicated that thicknesses of protein coronas and the aggregation behavior of AuNPs were closely related to their surface properties and protein structure. We also found that BSA and FIB underwent different conformational changes upon adsorption depending on the surface-modified Au NRs. Hence, these findings offered important insights into the essence of the interactions between NPs and proteins toward the development of safe and effective nanomaterials.