1.D.125. The Ligand-gated Ion-Channel Mimetic Nanopore Membrane with
an On-board Transmembrane Microbattery (LG-NP) Family
Synthetic nanopore membranes that mimic the function of biological ligand-gated ion channels require a situation in which the channel exists in a membrane with a transmembrane ion gradient to creat a membrane potential. A hydrophobic alumina nanopore membrane can be switched from an 'off' state to an 'on' state by exposure of the membrane to hydrophobic ionic surfactants. In these experiments, external electrodes and an external power supply have been used to drive the ion current when the membrane was in its 'on' state. In biological channels there are no electrodes, and the ion current is driven by an electrochemical potential difference across the cell membrane. Trofin et al. 2004 mimiced the function of a ligand-gated ion channel by applying a porous battery cathode film to one face of the hydrophobic alumina membrane and a porous battery anode film to the other face. Hence, by analogy to the naturally occurring channel, Trofin et al. 2004 have designed a membrane with a built in electrochemical potential difference across the membrane. They showed that in the absence of the ligand (the hydrophobic ionic surfactant), the membrane is in its 'off' state, and the electrochemical potential difference cannot be utilized to drive a transmembrane ion current. In contrast, when the ligand is detected, the membrane switches to its 'on' state and the transmembrane battery discharges, producing a corresponding transmembrane ion current.