Differences in corona formation of catalase immobilised on gold and silver nanoparticles

Abstract The adsorption process of proteins on nanoparticles (NPs) is spontaneous and depends on many factors, including the NP composition, size, shape, dispersity, and surface chemistry, as well the protein type, its chemical structure, affinity to NP surface, size, shape, availability of functional groups, etc. As a result, prediction of the adsorption process and the surface coverage of NPs with proteins remains a challenge. The theoretical coverage can obviously be calculated on the basis of geometric considerations, assuming that proteins remain globular on the NP surface; however, this is only a model approach, which does not always coincide with experimental results. Hence, experimental techniques are needed to characterise bioconjugates and to determine how many protein molecules bind to a NP surface. In this paper, we quantitatively characterise the surface coverage of NPs with catalase on the basis of polyacrylamide gel electrophoresis (PAGE). The surface coverage was investigated on two types of metallic NPs with a diameter equal 13 nm: i) gold and ii) silver. The obtained results prove that the protein corona formation significantly depends on the chemical composition of NPs and is difficult to predict how many protein molecules have to be incorporated into the colloid to attain assumed surface coverage.