Electronic Properties of a Graphene Device with Peptide Adsorption: Insight from Simulation
Electronic Properties of a Graphene Device with Peptide Adsorption: Insight from Simulation
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DOI：
10.1021/am401731c
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发表时间：
2013-08-14
影响因子：
9.5
通讯作者：
Farmer, Barry L.
中科院分区：
文献类型：
--
作者：
Akdim, Brahim;Pachter, Ruth;Farmer, Barry L.
为了解释单层石墨烯掺杂对场效应晶体管(GFET)中HSSYWYAFNNKT(P1)和HSSAAAAFNNKT(P1-3A)吸附的影响，我们采用了一种组合计算方法，用分子动力学模拟了多肽的吸附，用密度泛函理论计算确定了最低能量构型。在此基础上，对杂化材料的电子结构和输运进行了计算。我们证明了P1中芳香族残基和近端多肽骨架在石墨烯表面的pi-pi堆积对p掺杂有一定的影响。这些结果与我们对GFET的p掺杂的实验观察是一致的，即使在24小时的热处理过程中也是如此。在(P1-3A)中，当三个芳香族残基被Ala取代后，实验上观察到比p掺杂有相当大的减少，这表明与未吸附的器件相比，n掺杂，但没有基于原子MD模拟结构来解释。为了在更长的模拟时间内对P1-3A的吸附有一个定性的了解，这可能不同于芳香氨基酸残基在表面的快速锚定，我们分析了500 ns的平衡粗粒模拟。计算表明，Ala残基从表面解吸，这反过来可能影响电荷转移，但要完全解释n掺杂的机理，需要澄清各种芳香族残基之间的差异，这取决于肽的组成，以及包括底物和环境的影响，这将在未来的工作中考虑。
In this work, to explain doping behavior of single-layer graphene upon HSSYWYAFNNKT (P1) and HSSAAAAFNNKT (P1-3A) adsorption in field-effect transistors (GFETs), we applied a combined computational approach, whereby peptide adsorption was modeled by molecular dynamics simulations, and the lowest energy configuration was confirmed by density functional theory calculations. On the basis of the resulting structures of the hybrid materials, electronic structure and transport calculations were investigated. We demonstrate that pi-pi stacking of the aromatic residues and proximate peptide backbone to the graphene surface in P1 have a role in the p-doping. These results are consistent with our experimental observation of the GFET's p-doping even after a 24-h annealing procedure. Upon substitution of three of the aromatic residues to Ala in (P1-3A), a considerable decrease from p-doping is observed experimentally, demonstrating n-doping as compared to the nonadsorbed device, yet not explained based on the atomistic MD simulation structures. To gain a qualitative understanding of P1-3A's adsorption over a longer simulation time, which may differ from aromatic amino acid residues' swift anchoring on the surface, we analyzed equilibrated coarse-grain simulations performed for 500 ns. Desorption of the Ala residues from the surface was shown computationally, which could in turn affect charge transfer, yet a full explanation of the mechanism of n-doping will require elucidation of differences between various aromatic residues as dependent on peptide composition, and inclusion of effects of the substrate and environment, to be considered in future work.