H + -type and OH - -type biological protonic semiconductors and complementary devices

Abstract

Proton conduction is essential in biological systems. Oxidative phosphorylation in mitochondria, proton pumping in bacteriorhodopsin, and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H + hop along chains of hydrogen bonds between water molecules and hydrophilic residues - proton wires. These wires also support the transport of OH - as proton holes. Discriminating between H + and OH - transport has been elusive. Here, H + and OH - transport is achieved in polysaccharide- based proton wires and devices. A H + - OH - junction with rectifying behaviour and H + -type and OH - -type complementary field effect transistors are demonstrated. We describe these devices with a model that relates H + and OH - to electron and hole transport in semiconductors. In turn, the model developed for these devices may provide additional insights into proton conduction in biological systems.