Protein Integrated, Functionally Active Silver Nanoplanar Structures for Enhanced SPR

In an alternative approach to achieving nanoparticle-based enhanced surface plasmon resonance (SPR), we present a simple protein seeding-based method for the synthesis of a protein integrated, surface active silver nanoplanar structure, where the protein is cocrystallized with silver. The growth kinetics of this integrated structure has been probed by X-ray diffraction and Raman spectroscopy, which show a spherical to prismatic transition within a three minute growth span. The SPR activity is directly proportional to the tip sharpness of the nanostructure due to the localized surface plasmon resonance (LSPR) phenomenon. This biometallization process depends on the size, shape, and chemical nature of the interacting protein as demonstrated by comparing the results for different model proteins. Moreover, the protein remains functionally intact when embedded in the nanostructured SPR surface. Taking horseradish peroxidase (HRP) as a model protein, we have demonstrated a very high SPR binding profile against anti-HRP compared to direct binding of HRP to the gold surface.