The influence of shape and charge on protein corona composition in common gold nanostructures

With increasing importance of gold nanoparticles (AuNPs) in the medical field, the understanding of their interactions in biological environments is essential. It is known that the exposure to biological fluids of particles in the nanometric range leads to accumulation of proteins on the particle surface proximity, generating the so-called protein corona. This fact can completely change the properties of AuNPs, thus drastically influencing the characteristics and intended purpose of the particles. Therefore, deep insight on the formation and composition of this protein corona is of extreme importance. Between the different factors that can alter the corona formation, our study focuses on the influence of the shape and particle surface charge. In detail, four different shapes of nanometrical scale (spheres, rods, stars and cages) of comparable size were used, all of them stabilized with three different heterofunctionalized poly(ethylene glycol) thiol (R-PEG-SH) linkers (R = OCH3, COOH or NH2) to check the effect of charge as well. After incubation with human serum, abundant proteins were identified via liquid chromatography-electrospray ionization-tandem mass spectroscopy (LC ESI MS/MS) and compared in terms of their relative abundance. On the basis of statistical evaluations, the shape of our AuNPs showed a greater influence than the surface charge. Especially, cage-shaped AuNPs showed a lower amount of total corona proteins. This shape showed differences in the abundances of individual proteins like albumin, vitronectin and members of the complement system. These results indicate that nanocages could present an improved biocompatibility compared with the other shapes due to the high curvature areas and dense ligation on the flat surfaces that could hinder opsonisation and fast removal by the immune system.