  Antibodies are affinity proteins with a wide spectrum of applications in
analytical and therapeutic biology. Proteins showing specific recognition for a
chosen molecular target can be isolated and their encoding sequence identified
in vitro from a large and diverse library by phage display selection. In this
work, we show that this standard biochemical technique rapidly yields a
collection of antibody protein binders for an inorganic target of major
technological importance: crystalline metallic gold surfaces. 21 distinct
anti-gold antibody proteins emerged from a large random library of antibodies
and were sequenced. The systematic statistical analysis of all the protein
sequences reveals a strong occurrence of arginine in anti-gold antibodies,
which corroborates recent molecular dynamics predictions on the crucial role of
arginine in protein/gold interactions. Once tethered to small gold
nanoparticles using histidine tag chemistry, the selected antibodies could
drive the self-assembly of the colloids onto the surface of single crystalline
gold platelets as a first step towards programmable protein-driven construction
of complex plasmonic architectures. Electrodynamic simulations based on the
Green Dyadic Method suggest that the antibody-driven assembly demonstrated here
could be exploited to significantly modify the plasmonic modal properties of
the gold platelets. Our work shows that molecular biology tools can be used to
design the interaction between fully folded proteins and inorganic surfaces
with potential applications in the bottom-up construction of plasmonic hybrid
nanomaterials.
