"This is very intriguing since the biocompatible and water-soluble peptide nanotubes are formed under mild conditions and are inexpensive and easy to manufacture," researcher Ehud Gazit told nanotechweb.org. "Furthermore, the chemical nature of the peptide tubes allows their facile biological and chemical modification for further sensing applications."

Gazit and colleagues coated a graphite electrode with diphenylalanine nanotubes and placed it in a solution of potassium hexacyanoferrate. The nanotube coating increased the current signal that the electrode produced by a factor of around 2.5. The researchers believe this effect was due to the increased surface area that the nanotubes provided.

"The peptide nanotubes' electrochemical sensing [technique] can serve as a platform for ultrasensitive detection of biological and chemical agents," said Gazit. "Potential applications include environmental monitoring, and medical applications as a sensitive sensor per se or as part of a micro- or nano-scale medical appliance such as an implanted insulin pump. Moreover, such electrochemical sensors may serve in homeland security detection of biological and chemical warfare agents."

The researchers reckon that the peptide nanotubes have advantages over carbon nanotubes because they are easy to make, soluble in water, and can be chemically modified by targeting their amino or carboxyl groups.

Now Gazit and colleagues are studying the use of peptide nanotube-based sensors in real-life applications. "One of the key directions is the decoration of the nanotubes with specific biological agents by a novel method," said Gazit. "This will allow us to introduce new functionality and specificity to the tubes while keeping their unique properties for advanced biosensing applications."

The researchers reported their work in Nano Letters.