Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer

Lee, Donggeun; Jung, Woo Hyuk; Lee, Suho; Yu, Eui-Sang; Lee, Taikjin; Kim, Jae Hun; Song, Hyun Seok; Lee, Kwan Hyi; Lee, Seok; Han, Sang-Kook; Choi, Myung Chul; Ahn, Dong June; Ryu, Yong-Sang; Kim, Chulki

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. 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.