Controlled rod nanostructured assembly of diphenylalanine and their optical waveguide properties.

Diphenylalanine (FF) microrods were obtained by manipulating the fabrication conditions. Fourier transform infrared (FTIR), circular dichroism (CD), fluorescence (FL) spectroscopy, and X-ray diffraction (XRD) measurements revealed the molecular arrangement within the FF microrods, demonstrating similar secondary structure and molecular arrangement within FF microtubes and nanofibers. Accordingly, a possible mechanism was proposed, which may provide important guidance on the design and assembly manipulation of peptides and other biomolecules. Furthermore, characterization of a single FF microrod indicates that the FF microrod can act as an active optical waveguide material, allowing locally excited photoluminescence to propagate along the length of the microrod with coupling out at the microrod tips.