Synthetic DNA nanopores are attracting attention as alternatives to conventional biological nanopores in nanopore sensors because of the high designability of their pore structures and functionability. However, the efficient insertion of DNA nanopores into a planar bilayer lipid membrane (pBLM) remains challenging. Although hydrophobic modifications such as the use of cholesterol are required to insert DNA nanopores into pBLMs, these modifications also induce negative effects, including the undesired aggregation of DNA structures. Herein, we describe an efficient method to insert DNA nanopores into pBLMs and measure the channel currents of DNA nanopores using a DNA nanopore-tethered gold electrode. When the pBLM is formed at the electrode tip by immersing the electrode into a layered bath solution comprising an oil/lipid mixture and an aqueous electrolyte, the electrode-tethered DNA nanopores are physically inserted into the pBLM. In this study, we designed a DNA nanopore structure that can be immobilized on the gold electrode based on a reported six-helix bundle DNA nanopore structure and prepared DNA nanopore-tethered gold electrodes. Thereafter, we demonstrated the channel current measurements of the electrode-tethered DNA nanopores, and a high insertion probability of the DNA nanopores was achieved. We believe that this efficient DNA nanopore insertion method can accelerate the application of DNA nanopores in stochastic nanopore sensors.
Keywords: DNA; gold needle electrode; ion current measurement; lipid bilayer; nanopore.