Ionic contrast across a lipid membrane

Despite technological advances in biomolecule detections, evaluation of molecular interactions via potentiometric devices under ion-enriched solutions has remained a long-standing problem. To avoid severe performance degradation of bioelectronics by ionic screening effects, we cover probe surfaces of field effect transistors with a single film of the supported lipid bilayer, and realize respectable potentiometric signals from receptor–ligand bindings irrespective of ionic strength of bulky solutions by placing an ion-free water layer underneath the supported lipid bilayer. High-energy X-ray reflectometry together with the circuit analysis and molecular dynamics simulation discovered biochemical findings that effective electrical signals dominantly originated from the sub-nanoscale conformational change of lipids in the course of receptor–ligand bindings.

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FIG: Electrical sensing in ionic environments and schematic of the SLB-assisted FET measurement setup

Beyond thorough analysis on the underlying mechanism at the molecular level, the proposed supported lipid bilayer-field effect transistor platform ensures the world-record level of sensitivity in molecular detection with excellent reproducibility regardless of molecular charges and environmental ionic conditions.

Lee, D., Jung, W.H., Lee, S. et al. Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer. Nat Commun 12, 3741 (2021). https://doi.org/10.1038/s41467-021-24122-8

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