  The characterization of protein-nanoparticle assemblies in solution remains a
challenge. We demonstrate a technique based on a graphene microelectrode for
structural-functional analysis of model systems composed of nanoparticles
enclosed in open-pore and closed-pore ferritin molecules. The method readily
resolves the difference in accessibility of the enclosed nanoparticle for
charge transfer and offers the prospect for quantitative analysis of
pore-mediated transport shed light on the spatial orientation of the protein
subunits on the nanoparticle surface, faster and with higher sensitivity than
conventional catalysis methods.
