Polyproline II-based helical peptides were adsorbed to silver nanocubes through a cysteine linker and induced circular dichroism (CD) in two of their plasmon resonance modes. Inversion of the peptide’s orientation with respect to the surface led to inversion of the plasmonic CD signal. This phenomenon could not be explained by the simple molecule–plasmon dipolar interaction model and could be due to the multipolar nature of the plasmon modes. Elongation of the polyproline peptide led to a significant increase of the induced CD signal. Surprisingly, the effect did not change with sharpening of the edges of the silver nanocubes. The change to a polyproline I helix caused nulling of the induced plasmonic CD.
Polyproline II-based helical peptides were adsorbed to silver nanocubes through a cysteine linker and induced circular dichroism (CD) in two of their plasmon resonance modes. Inversion of the peptide’s orientation with respect to the surface led to inversion of the plasmonic CD signal. This phenomenon could not be explained by the simple molecule–plasmon dipolar interaction model and could be due to the multipolar nature of the plasmon modes. Elongation of the polyproline peptide led to a significant increase of the induced CD signal. Surprisingly, the effect did not change with sharpening of the edges of the silver nanocubes. The change to a polyproline I helix caused nulling of the induced plasmonic CD.
