Direct insertion of an ion channel immobilized on a soft agarose gel bead into a lipid bilayer: an optimized method

In this paper, we report the development of a device that improves the conventional artificial lipid bilayer method and can measure channel currents more efficiently. Ion channel proteins are an attractive research target in biophysics, because their functions can be measured at the single-molecule level with high time resolution. In addition, they have attracted attention as targets for drug discovery because of their crucial roles in vivo. Although electrophysiological methods are powerful tools for studying channel proteins, they suffer from low measurement efficiency and require considerable skill. In our previous paper, we reported that by immobilizing channel proteins on agarose gel beads and forming an artificial lipid bilayer on the bead surface, we simultaneously solved two problems that had been hindering the efficiency of the artificial bilayer method: the time-consuming formation of artificial lipid bilayers and the time-consuming incorporation of channels into artificial bilayers. Previous studies have utilized crosslinked hard beads; however, here we show that channel current measurement can be achieved more simply and efficiently using non-crosslinked soft beads. In this study, we detailed the process of immobilizing channel proteins on the surface of non-crosslinked beads through chemical modification, allowing us to measure their channel activity. This method enables current measurements without the need for stringent bead size selection or high negative pressure.