The University of Queensland, School of Chemical Engineering, Qld 4072, Australia.
The University of Queensland, School of Mathematics and Physics & Centre of Organic Photonics and Electronics, The University of Queensland, Qld 4072, Australia.
Acta Biomater. 2018 Mar 15;69:1-30. doi: 10.1016/j.actbio.2018.01.007. Epub 2018 Jan 31.
Electron transfer is central to cellular life, from photosynthesis to respiration. In the case of anaerobic respiration, some microbes have extracellular appendages that can be utilised to transport electrons over great distances. Two model organisms heavily studied in this arena are Shewanella oneidensis and Geobacter sulfurreducens. There is some debate over how, in particular, the Geobacter sulfurreducens nanowires (formed from pilin nanofilaments) are capable of achieving the impressive feats of natural conductivity that they display. In this article, we outline the mechanisms of electron transfer through delocalised electron transport, quantum tunnelling, and hopping as they pertain to biomaterials. These are described along with existing examples of the different types of conductivity observed in natural systems such as DNA and proteins in order to provide context for understanding the complexities involved in studying the electron transport properties of these unique nanowires. We then introduce some synthetic analogues, made using peptides, which may assist in resolving this debate. Microbial nanowires and the synthetic analogues thereof are of particular interest, not just for biogeochemistry, but also for the exciting potential bioelectronic and clinical applications as covered in the final section of the review.
Some microbes have extracellular appendages that transport electrons over vast distances in order to respire, such as the dissimilatory metal-reducing bacteria Geobacter sulfurreducens. There is significant debate over how G. sulfurreducens nanowires are capable of achieving the impressive feats of natural conductivity that they display: This mechanism is a fundamental scientific challenge, with important environmental and technological implications. Through outlining the techniques and outcomes of investigations into the mechanisms of such protein-based nanofibrils, we provide a platform for the general study of the electronic properties of biomaterials. The implications are broad-reaching, with fundamental investigations into electron transfer processes in natural and biomimetic materials underway. From these studies, applications in the medical, energy, and IT industries can be developed utilising bioelectronics.
电子转移是细胞生命的核心，从光合作用到呼吸作用。在无氧呼吸的情况下，一些微生物有可以用来远距离传输电子的细胞外附属物。在这个领域中，两个被广泛研究的模式生物是希瓦氏菌（Shewanella oneidensis）和脱硫弧菌（Geobacter sulfurreducens）。特别是脱硫弧菌纳米线（由菌毛纳米丝组成）如何能够实现其显示的令人印象深刻的自然导电性壮举，存在一些争议。在本文中，我们概述了电子通过非定域电子传输、量子隧穿和跳跃转移的机制，这些机制与生物材料有关。我们描述了这些机制以及在自然系统中观察到的不同类型导电性的现有实例，以便为理解研究这些独特纳米线的电子传输性质所涉及的复杂性提供背景。然后，我们引入了一些使用肽制成的合成类似物，这些类似物可能有助于解决这一争议。微生物纳米线及其合成类似物不仅对生物地球化学有意义，而且对最后一节中涵盖的令人兴奋的生物电子和临床应用也有意义。
为了进行呼吸作用，一些微生物有可以远距离传输电子的细胞外附属物，例如异化金属还原细菌脱硫弧菌。脱硫弧菌纳米线如何能够实现其显示的令人印象深刻的自然导电性壮举存在很大争议：这一机制是一个基本的科学挑战，对环境和技术都有重要影响。通过概述对这种基于蛋白质的纳米纤维的机制进行研究的技术和结果，我们为一般研究生物材料的电子性质提供了一个平台。影响范围广泛，对自然和仿生材料中的电子转移过程进行了基础研究。从这些研究中，可以开发出利用生物电子学的医疗、能源和 IT 行业的应用。
