多血红素蛋白生物电子结中3纳米非共振相干电子输运
Off-resonant coherent electron transport over three nanometers in multi-heme protein bioelectronic junctions
摘要：
多血红素细胞色素（MHC）是细菌生物体用来在细胞内和细胞之间穿梭电子的迷人蛋白质。当放置在固态电子结中时，它们支持超过几纳米的温度无关电流，与其他大小相当的氧化还原蛋白质相比高出三个数量级。为了从微观上深入了解它们惊人的高电导率，我们在本文中首次提出了这种类型的电流-电压计算，用于夹在两个Au（111）电极之间的MHC，并辅以光发射光谱实验。我们发现，通过非共振相干隧穿介导的大量的蛋白质的价带轨道，强烈离域血红素和蛋白质残基，有效地“门控”两个电极之间的电流进行传导。这幅图与水溶液中相同蛋白质所支持的主要电子跳跃机制有着深刻的不同。我们的研究结果意味着，在MHC结的电流输出可以进一步增加在谐振制度，例如通过施加栅极电压，使这些蛋白质非常有趣的下一代生物纳米电子器件。
英文摘要：
Multi-heme cytochromes (MHC) are fascinating proteins used by bacterial organisms to shuttle electrons within and between their cells. When placed in a solid state electronic junction, they support temperature-independent currents over several nanometers that are three orders of magnitude higher compared to other redox proteins of comparable size. To gain microscopic insight into their astonishingly high conductivities, we present herein the first current-voltage calculations of its kind, for a MHC sandwiched between two Au(111) electrodes, complemented by photo-emission spectroscopy experiments. We find that conduction proceeds via off-resonant coherent tunneling mediated by a large number of protein valence-band orbitals that are strongly delocalized over heme and protein residues, effectively "gating" the current between the two electrodes. This picture is profoundly different from the dominant electron hopping mechanism supported by the same protein in aqueous solution. Our results imply that current output in MHC junctions could be even further increased in the resonant regime, e.g. by application of a gate voltage, making these proteins extremely interesting for next-generation bionanoelectronic devices.
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