Biodegradable peptide functionalization layers for contactless electrical sensing of volatile organic compounds
Hadar Peled, Gilad Levy and Nurit Ashkenasy
Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva, Israel
Analysis of volatile organic compound (VOCs) composition in breath samples can signify health conditions related to metabolic or infectious diseases. Functionalization of the sensor surface with peptides is an attractive approach for improved detection. In such configuration, the peptides’ versatility and modularity is used for designing peptides with sensitivity and selectivity towards specific VOCs. In this work, I demonstrate that VOC binding to the peptide can modulate the surface work function and consequently transduce the binding interactions into an electrical signal that can be read in a contactless manner. The sensing signal in our device is obtained by monitoring the contact potential difference (CPD) between the sensor surface and a reference electrode. I will show that the functionalization of a gold surface with a specific peptide receptor allows for a significant improvement of ethanol detection. The optimization of peptide assembly conditions (i.e., peptide concentration) for improved detection will be presented. I will further show that the CPD signal is linearly proportional to the density of ethanol molecules bound to the surface, and that the sensitivity is higher than the sensitivity obtained with the commonly used quartz crystal microbalance (QCM) technique. Our findings show the dual role of peptide functionalization both for improved sensitization and for signal transduction, making this functionalization attractive for the fabrication of high performance VOC sensors.