Peptide-functionalized Single-walled Carbon Nanotube Field-effect Transistors for Monitoring Volatile Organic Compounds in Breath

This paper presents peptide-functionalized carbon nanotube (CNT) field-effect transistors (FETs) aimed to discriminate four different volatile organic compounds (VOCs) (isopropyl alcohol, acetone, isoprene, and toluene) found in breath. Previous CNT FETs for VOC detection have shown detection of explosives or food quality indicators. Sensing human breath gases related to an individual's health and/or performance, however, has not yet been explored by using peptide-based CNT FETs. In addition, previous CNT FETs have required complicated immobilization techniques, such as design of fusion peptides (combination of known peptides with linker residuals), or special chemical treatments for the CNT functionalization. The present, novel CNT FETs are functionalized with 12-mer peptides identified using phage display. The identified peptides have an affinity to CNTs, making them easy to be functionalized without additional conjugate linkers or surface modifications. From VOCs exposure test results, the present CNT FETs, utilizing the specific peptides, successfully showed not only discrimination of the four different breath-related VOCs, but also the advantageous characteristics of being easily functionalized. The proposed CNT FETs have potentials for wearable breath monitoring applications such as personal health diagnosis and real-time human performance assessments.