Observation of odd–even effect in 1-alcohols through pentapeptide-coated quartz crystal microbalance sensors with molecular docking study

The discrimination between odd and even carbon chain molecules is crucial in detecting odd chain metabolites resulting from impaired biosynthetic processes. However, the discrimination of these metabolomes via gas sensors presents significant challenges due to the lack of connection between material–gas interaction and odd–even carbon chain molecules. In this study, a homologous series of 1-alcohols is systematically investigated, quantitatively comparing the measured signals obtained using pentapeptide-coated gas sensors and pentapeptide–gas interactions calculated via molecular docking simulations. The pentapeptide-coated gas sensor exhibits a clear odd–even effect in both absorption and desorption processes, demonstrating better discrimination between odd- and even-numbered carbon compounds. The results indicate that the odd–even effect during the absorption process is closely associated with the hydrophobic interaction between a pentapeptide and a gas molecule, while the interactions affecting the desorption phase may vary depending on the pentapeptide properties. The insights into the molecular interactions involved in the odd–even effect will facilitate the development of materials for detecting odd chain metabolites, which can enhance the accuracy of gas-sensing technologies toward health monitoring applications.