2 min readDevelopment of “Cellular Membrane-FET (Lipid-FET)” for Sensitivity of Biosensor

Seoul, Republic of Korea — The Korean team of researchers successfully developed a proprietary biosensor technology with significantly enhanced molecular sensitivity using the artificial lipid membrane that mimics cellular membrane. The Korea Institute of Science and Technology announced that the research team led by Dr. Yong-Sang Ryu from the Brain Science Institute and Dr. Chul Ki Kim from the Sensor System Research Center, in collaboration with the research team led by Professor Dong June Ahn from the Department of Chemical and Biological Engineering at Korea University, developed a technology to enhance the molecular detectability over the potentiometric field-effect transistor (FET) surface via ion-impermeation across the lipid membrane.
* FET : Transistor that controls the current flow based on the principle of applying voltage to electrode to create a channel for electron(-) or proton(+) flow based on the electric field.

It has been somewhat challenging to commercialize the FET-based molecular detection technology, a sensor technology using electric signals, despite its benefits in the detection of various molecules such as viruses, proteins, and DNA. This is mainly due to the ultra-thin detection ranges for molecular detection under high concentration of ions or electric charge of the analyte solution.

For instance, in one drop of blood, the effective detection ragne from which molecules can be detected over the potentiometric sensor probe is approximately 1 nm, which is thinner than the molecule to be detected and analyzed; therefore, it is difficult to detect the electric signal even if the molecule comes in contact with the sensing probe. To overcome this hurdle, various strategies, such as diluting the analyte solution up to 100,000 fold to enhance the molecular detection, have been used; however, these strategies have not been successful.

Therefore, the research team proposed the use of the model membrane to overcome this obstacle. The cellular membrane of humans not only controls the ion concentration of the internal and external environment but also prevents a high concentration of ions from entering the cell. The team thus focused on this specific characteristic of the cellular membrane-mimicking system. After repeated tests for applying the cellular membrane to the surface of the FET-based molecular detection chip, it was confirmed that molecule detection is available without additional pretreatment, even in a high-concentration ionic solution.

With this new technology known as “Membrane coated-FET (lipid-FET),” molecules suspended in highly ionic concentrated solution, to a level of human blood, can be detected with higher sensitivity compared to that of the existing sensor, and dilution of the solution up to 100,000-fold is not required. This was confirmed to be the highest performance among all FET reported so far globally. Research team expects that this technology can be used to diagnose various diseases related matters such as dementia-associated proteins, but it is also a platform technology with extensive applicability as biosensors in diverse fields including medicine, healthcare, and the environment for detecting viral infections and microplastics.

Dr. Yong-Sang Ryu from KIST introduced the research achievement as “Molecule detection via Lipid-FET with ionic contrast across the membrane can be instantly applied to all the existing potentiometric sensor platforms that use an electric field to detect molecules”. Dr. Chul Ki Kim from KIST further added that “researches for applying the technology to various research fields such as diseases known to be caused by mutated proteins attached to cellular membranes like Alzheimer’s disease, Parkinson’s’ disease, and diabetes, and technology to rapidly and precisely detect an extremely small number of infectious viruses such as COVID-19 and influenza are being conducted in parallel.” Professor Dong June Ahn from Korea University hoped that “the technology can be expanded to contribute to solving societal problems and improving the overall quality of human life.”

This research was funded by the Ministry of Science and ICT as a KIST‘s institutional research program and mid-career researcher project and the creative materials discovery program of the National Research Foundation of Korea. The research outcome has been published in the recent issue of ‘Nature Communications’ (IF: 14.919, JCR top 4.795% in the field), one of the journals in the field of convergence technology.

Article adapted from a National Research Council of Science and Technology news release.

Publication: Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer. Lee, D et al. Nature Communications (June 18, 2021): Click here to view.

Biosensor, field-effect transistor

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