Nucleobase sensing using highly-sensitive surface-enhanced Raman spectroscopy templates comprising organic semiconductor peptide nanotubes and metal nanoparticles

Templates formed from aligned diphenylalanine nanotubes with plasmon-active metal nanoparticles are a promising nanocomposite for large-scale, rapid, stable, and cost-effective surface- enhanced Raman spectroscopy (SERS) substrates. The high sensitivity of such templates arises from an arrangement of densely packed plasmon-active silver nanoparticles that enhance the localized electromagnetic field and allow the detection of the nucleobases adenine, cytosine, thymine, uracil, and guanine at concentrations in the range 10(-5) to 10(-9) M. Blinking of the SERS signal is observed, indicating sensitivity down to the single or few molecule limit. Such blinking could result from charge transfer processes. These results demonstrate the potential for using aligned diphenylalanine nanotube-metal nanoparticle templates for practical monitoring of biomolecules and are promising initial steps toward the use of peptide nanotube-based templates in diagnostic sensing applications.