The Lipid Bilayer Principle and Molecular Electronics

On the subject of molecular electronics and biocomputers, one recalls the first symposium held in Budapest, Hungary in 1987. At that meeting, one of the authors suggested that ‘Life is molecular electronics!’ This is actually an extension of a remark made by Albert Szent-Gyorgyi who said a quarter of a century earlier that ‘life, as we know it, is nothing but a movement of electrons’[1]. Indeed, in the 1970s the U. S. Air Force had a program called ‘Molecular Electronics’, because the scientists then thought they could find something in the basic structure of the molecule that would serve the function of traditional resistors, capacitors, diodes, etc. This was owing to a relentless decrease in the size of silicon-based microelectronics devices. The most important among these are limitations imposed by quantum-size effects and instabilities introduced by thermal fluctuations. As a result, these inherent problems of the day have prompted scientists to look for alternative choices. Advancement in the understanding of biosystems such as photosynthetic apparatus and genetic engineering has allowed attention to be focused on the use of biomolecules (pigments, enzymes, receptors, etc.). Realization of the power of self-assembly principles has opened a novel approach for designing and assembling molecular structures with desired intricate architecture. The utility of molecules such as DNA as a three-dimensional, high-density memory element and its capability for molecular computing have been fully recognized but not yet realized. Today, three overlapping areas of molecular electronics research are: materials science, fabrication t echnology, a nd de vice a rchitecture [2]. These a re b ased o n t he fusion of ideas and disciplines between membrane biophysics and molecular cell biology on one hand, and advances in microelectronics on the other. For instance, the visual receptor of the eye is one of basic structures of Nature’s sensors and devices. Therefore, preparation and characterization of ordered ultrathin lipid films (∼ 5-6 nm thick) has attracted considerable attention because of the possibility of controlling order and interactions at the molecular level. In particular, bilayer lipid membranes (BLMs) prepared by self-assembly are attractive for several exciting applications.