Poster Y20 - Insect Odorant Integrated Graphene Field Effect Biosensor for Small Organic Compounds Detection

Introduction: The development of portable and highly sensitive electronic biosensors for small organic compound (SOC) detection holds significant promise (Cheema et al., 2021) due to its potential ease of integration and detection of a spectrum of biological and non-biological SOCs. This study presents the integration of a highly sensitive single atomic layer graphene field effect transistor (gFET) with homotetrameric odorant, MhOr5, derived from Machilis hrabei, aimed at SOC detection (Figure 1).

Materials and

Methods: The MhOR5 protein was synthesized by CRO, Calixar, utilizing Baculovirus-transfected HEK293f cells to enable freestyle expression. Following purification, the protein was immobilized onto a graphene field effect transistor (gFET) using carbodiimide chemistry with 1-pyrene butyrate n-hydroxysuccinimide (PBASE). The interaction between MhOR5 and various small molecules was then monitored in real-time by measuring Dirac Voltage, employing different concentrations of the molecules. To assess the specificity of detection, the gFET-based sensors were subjected to binding kinetics and dissociation analysis using tastant D-Glucose and odorant Isoeugenol with Eugenol. Furthermore, the capability of the MhOR5-integrated gFET sensor to detect a range of small molecules was evaluated.

Results, Conclusions, and Discussions: The resultant MhOr5-integrated gFET sensors were subjected to varying concentrations (0, 200 nM to 10 mM) of SMCs including Eugenol and DEET, with real-time recording of Dirac voltage. A concentration-dependent Dirac voltage shift exceeding 3mV to 60 mV in response to Eugenol, a strong binder to MhOR5, compared to D-glucose was observed (Figure 2). Further analysis of 16 different molecules showed the equivalent magnitude of SOCs association as reported by del Mármol, 2021 except for three outliers (Isobutyl acetate, Sulcatone, and Trimethyl thiazole), which might be due to MhOr5-analytes complex on graphene surface was unable to modulate the conductivity significantly (Figure 3). Activity index analysis demonstrated a correlation with earlier electrophysiological analysis. We have shown the great potential of the reported sensor to be deployed as a detection tool to monitor biothreats and infectious diseases specific SOCs in clinical setups, and on-field operations.

Acknowledgements (Optional): We are thankful to the Gate Foundation for financial support for this project. CardeaBio/Paragraf for technical assistance.