Peptide-Functionalized Graphene Biosensors

Gas sensing based on graphene field-effect transistors (GFETs) has garnered significant interest due to their high sensitivity and potential applications in environmental monitoring, healthcare, food, and cosmetic industries. Recent advancements in GFETs aim to establish an artificial sense of smell by mimicking olfactory receptors with electronic devices. While using olfactory receptors on GFETs for odor sensing is straightforward, synthetic molecules that mimic these receptors offer more robust performance. In this presentation, the design of three new peptides is introduced, consisting of two domains: a bio-probe targeting specific molecules and a molecular scaffold [1]. These peptides, rationally designed based on olfactory receptor motifs, self-assemble into a molecular thin film on GFET.<br/>To demonstrate biosensing capabilities, limonene, methyl salicylate, and menthol were employed as representative odor molecules of plant flavors. The peptides exhibited distinct conductivity changes in GFETs upon binding to these odor molecules at various solution concentrations, revealing unique dynamic response signatures [2]. The kinetic response of each peptide showed characteristic time constants during adsorption and desorption, supported by principal component analysis. This demonstration paves the way for future peptide-array sensors with multi-sequence peptides, enhancing odor detection systems' selectivity.<br/>Furthermore, in contrast to the above liquid-phase sensing, gas-phase graphene sensors under environmental conditions were demonstrated by introducing peptide-functionalized graphene sensors that mitigate undesired responses to humidity changes [3]. Humidity plays a significant role in facilitating the selective detection of odorant molecules by peptides, enabling precise and specific detection. The sensors demonstrate notable enantioselectivity, achieving a remarkable 35-fold signal contrast between d- and l-limonene. Additionally, principal component analysis of the obtained data exhibited distinct responses to various biogenic volatile organic compounds, proving their versatility and robustness in odor detection.<br/>By acting as both a bioprobe and an electrical signal transducer, the peptide layer presents a novel and effective strategy for selective odorant detection under normal atmospheric conditions using graphene sensors. This research provides valuable insights into developing practical odor-sensing technologies with broad applications, advancing the field of nanobioelectronics with graphene.<br/><br/>1. P. Li, et.al., ACS Applied Materials & Interfaces 11, 20670 (2019).<br/>2. C. Homma, et.al., Biosensors and Bioelectronics, 224, 115047 (2023).<br/>3. Y. Yamazaki, et.al., ACS Appl. Mater. Interfaces 16, 18564–18573 (2024).