Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
ACS Appl Mater Interfaces. 2022 Oct 5;14(39):44665-44675. doi: 10.1021/acsami.2c11263. Epub 2022 Sep 23.
Understanding the mechanisms of charge transport (CT) across biomolecules in solid-state devices is imperative to realize biomolecular electronic devices in a predictive manner. Although it is well-accepted that biomolecule-electrode interactions play an essential role, it is often overlooked. This paper reveals the prominent role of graphene interfaces with Fe-storing proteins in the net CT across their tunnel junctions. Here, ferritin (AfFtn-AA) is adsorbed on the graphene by noncovalent amine-graphene interactions confirmed with Raman spectroscopy. In contrast to junctions with metal electrodes, graphene has a vanishing density of states toward its intrinsic Fermi level ("Dirac point"), which increases away from the Fermi level. Therefore, the amount of charge carriers is highly sensitive to temperature and electrostatic charging (induced doping), as deduced from a detailed analysis of CT as a function of temperature and iron loading. Remarkably, the temperature dependence can be fully explained within the coherent tunneling regime due to excitation of hot carriers. Graphene is not only demonstrated as an alternative platform to study CT across biomolecular tunnel junctions, but it also opens rich possibilities in employing interface electrostatics in tuning CT behavior.
理解在固态器件中跨生物分子的电荷传输（CT）机制对于以可预测的方式实现生物分子电子器件是至关重要的。尽管人们普遍认为生物分子-电极相互作用起着重要的作用，但往往被忽视。本文揭示了在它们的隧道结中，石墨烯界面与储铁蛋白之间的相互作用在净 CT 中起着突出的作用。在这里，通过拉曼光谱证实，铁蛋白（AfFtn-AA）通过非共价的胺-石墨烯相互作用被吸附在石墨烯上。与金属电极的结相比，石墨烯对其本征费米能级（“狄拉克点”）的态密度趋近于零，而远离费米能级时则会增加。因此，正如通过对 CT 作为温度和铁负载函数的详细分析所推断的那样，载流子的数量对温度和静电充电（诱导掺杂）非常敏感。值得注意的是，由于热载流子的激发，温度依赖性可以完全在相干隧穿范围内得到解释。石墨烯不仅被证明是研究跨生物分子隧道结 CT 的替代平台，而且在利用界面静电来调整 CT 行为方面也具有丰富的可能性。
