Voltage-sensitive activities of ion-channel-coupled receptors integrated with budded baculovirus in bioelectronic nose devices

Abstract

Voltage-sensitive ion-channel-coupled receptors (ICCRs) are integrated with budded baculovirus particles (BBVs) for the amplification of bioelectronic nose signals via external voltage stimulation. Here, BBVs are employed as stable and uniform nanoscaffolds to introduce ICCRs into field-effect transistor devices, providing a direct alternative to conventional nanovesicle-based membrane platforms. ICCRs composed of human olfactory receptors (hOR2AG1) and potassium ion channels (Kir6.2) are transfected into BBV membranes, and then, the BBVs are immobilized on the channel region of a carbon nanotube field-effect transistor (CNT-FET). In this hybrid device, voltage-dependent ion channel gating behavior can be triggered by the stimulation of liquid gate voltages (VLG) to BBV membranes. The opening of ion channels leads to local fluctuations in junction potential between the BBV membrane and the CNT channel, which can be observed by changes in the channel conductance. Importantly, receptor-ligand binding activities of ICCR in BBV membranes can be modulated by applying different VLG values. The EC50 values for the receptor-ligand binding are estimated as 204 pM, 70.8 fM, and 1.4 fM for VLG of -80 mV, -120 mV, and -180 mV, respectively. This voltage-dependent modulation originates from changes in the BBV membrane potential, which alter the receptor binding affinity and reduce the ligand concentration required to induce a half-maximal sensor response into femtomolar ranges. Thus, our strategy can be utilized to achieve tunable signal amplification capabilities of bioelectronic nose device.