INFLUENCE OF VOLATILE ORGANIC COMPOUNDS ON PROTON CONDUCTION OF SELF-ASSEMBLED PEPTIDE FIBRILS

Analysis of volatile organic compounds (VOCs) of exhaled breath samples of patients has been demonstrated to be a very attractive way to diagnose illnesses, such as cancer, diabetes, and asthma, in recent years. Sensitive detection of VOCs is also a major challenge in environmental control due to the need to detect chemical pollutant byproducts of industrial processes, automobiles and homes. The quest for high sensitivity sensors has led to the implementation of nanomaterials as VOC sensing elements, making use of their high surface area and unique electrical and chemical properties. Most commonly such nanomaterials are treated with organic recognition elements to create specific receptors for selective VOCs. Here we present studies of the effect of VOCs on the electronic properties of cyclic peptides that undergo self-assembly into nanotubes with pronounced proton conductivity, which exhibit both large surface-area and design modularity, which makes them attractive choice for the development of novel type of VOCs sensors.

We show that the proton conductivity of the nanotubes is affected by the introduction of different type of VOCs, with apparent sensitivity to both polar (ethanol) and non-polar (petroleum ether) VOCs. The magnitude of the response to each of the tested VOCs is shown to depend on the peptide sequence, resulting in different recognition pattern for different sequences. Detailed characterizations, indicate that ethanol adsorption, for example, affects the concentration of charge carriers, leading to conductivity enhancement. These results show the feasibility and potential for the application of self-assembled peptide nanotubes as VOCs sensing elements.