Core–Shell Nanoplasmonic Sensing for Characterization of Biocorona Formation and Nanoparticle Surface Interactions

Surface properties of nanoparticles imposed by particle size, shape, and surface chemistry are key features that largely determine their environmental fate and effects on biological systems. Consequently, development of analytical tools to characterize surface properties of nanomaterials and their relation to toxicological properties must occur in parallel with applications. As a contribution to this quest, we present a nanoplasmonic sensing strategy that enables systematic in situ characterization of molecule–nanoparticle interactions under well-controlled conditions, in terms of both nanoparticle size and surface chemistry, with particular focus on the importance of surface faceting in crystalline nanoparticles. We assess the performance of our sensing strategy by presenting two case studies. (i) The first is protein corona formation on faceted Au core–SiO₂shell nanoparticles of different sizes, and thus different surface facet-to-edge ratios. Based on 2D and 3D models of the investigated structures, we find that for small particles the curved regions between adjacent facets dominate the response of the corona formation process, whereas the facets dominate the response in the large particle regime. (ii) The second is in situ functionalization of Au core–SiO₂ shell nanoparticle surfaces, and analysis of the subsequent protein repellent behavior. Due to the versatility of the presented sensing strategy in studies of nanoparticle surface properties, including in situ surface modifications, and their interactions with (bio)molecules during corona formation, we foresee it to become a valuable tool in the areas of nanomedicine and nanotoxicology.