Switching of the mechanism of charge transport induced by phase transitions in tunnel junctions with large biomolecular cages

摘要: Tunnel junctions based on Fe storing globular proteins are an interesting class of biomolecular tunnel due to their tunable ion loading, symmetrical structure and thermal stability, therefore attractive study the mechanisms charge transport (CT) at molecular level. This paper describes a temperature-induced change in CT mechanism across with large (∼25 nm diameter) E2-proteins bioengineered Fe-binding peptides from ferritin (E2-LFtn) mineralise ions form iron oxide nanoparticles (NPs) inside protein's cavity. The NPs provide accessible energy states that support high rates shallow activation barriers. Interestingly, changes abruptly, but reversibly, incoherent tunnelling (which is thermally activated) coherent activationless) E2-LFtn-based highest loading temperature 220–240 K. During this transition current density increases by factor 13 applied voltage V = −0.8 V. X-ray absorption spectroscopy indicates E2-LFtn cages undergo reversible phase transition; opens up new pathway changing activated activationless despite size associated distance for tunnelling.