  Thanks to the spontaneous interaction between noble metals and biological
scaffolds, nanomaterials with unique features can be achieved following
relatively straightforward and cost-efficient synthetic procedures. Here,
plasmonic silver nanorings are synthesized on a ring-like Peroxiredoxin (PRX)
protein and used to assemble large arrays of functional nanostructures. The PRX
protein drives the seeding growth of metal silver under wet reducing
conditions, yielding nanorings with outer and inner diameters down to 28 and 3
nm, respectively. The obtained hybrid nanostructures can be deposited onto a
solid-state membrane in order to prepare plasmonic nanopores. In particular,
the interaction between graphene and PRX allows for the simple preparation of
ordered arrays of plasmonic nanorings on a 2D-material membrane. This
fabrication process can be finalized by drilling a nanometer scale pore in the
middle of the ring. Fluorescence spectroscopic measurements have been used to
demonstrate the plasmonic enhancement induced by the metallic ring. Finally, we
support the experimental findings with some numerical simulations showing that
the nanorings are endowed with a remarkable plasmonic field within the cavity.
Our results represent a proof of concept of a fabrication process that could be
suitable for nanopore-based technologies such as next-generation sequencing and
single-molecule detection.
