Department of Physics, University of Illinois at Urbana-Champaign , 1110 W Green Street, Urbana, Illinois 61801, United States.
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , 1304 W Green Street, Urbana, Illinois 61801, United States.
J Phys Chem B. 2017 Feb 23;121(7):1684-1706. doi: 10.1021/acs.jpcb.6b10165. Epub 2017 Feb 10.
Self-assembled aggregates of peptides containing aromatic groups possess optoelectronic properties that make them attractive targets for the fabrication of biocompatible electronics. Molecular-level understanding of the influence of microscopic peptide chemistry on the properties of the aggregates is vital for rational peptide design. In this study, we construct a coarse-grained model of Asp-Phe-Ala-Gly-OPV3-Gly-Ala-Phe-Asp (DFAG-OPV3-GAFD) peptides containing OPV3 (distyrylbenzene) π-conjugated cores explicitly parameterized against all-atom calculations and perform molecular dynamics simulations of the self-assembly of hundreds of molecules over hundreds of nanoseconds. We observe a hierarchical assembly mechanism, wherein approximately two to eight peptides assemble into stacks with aligned aromatic cores that subsequently form elliptical aggregates and ultimately a branched network with a fractal dimensionality of ∼1.5. The assembly dynamics are well described by a Smoluchowski coagulation process, for which we extract rate constants from the molecular simulations to both furnish insight into the microscopic assembly kinetics and extrapolate our aggregation predictions to time and length scales beyond the reach of molecular simulation. This study presents new molecular-level understanding of the morphology and dynamics of the spontaneous self-assembly of DFAG-OPV3-GAFD peptides and establishes a systematic protocol to develop coarse-grained models of optoelectronic peptides for the exploration and design of π-conjugated peptides with tunable optoelectronic properties.
含有芳香族基团的自组装肽聚集物具有光电性质，这使得它们成为制造生物相容性电子设备的有吸引力的目标。从分子水平上了解微观肽化学对聚集物性质的影响对于合理的肽设计至关重要。在这项研究中，我们构建了一个含有 OPV3（二苯乙烯）π 共轭核心的粗粒化模型，该模型是针对全原子计算进行显式参数化的，并对数百个分子在数百纳秒内的自组装进行了分子动力学模拟。我们观察到一种分层组装机制，其中大约两到八个肽组装成具有对齐的芳香核的堆叠，随后形成椭圆形聚集体，最终形成具有分形维数约为 1.5 的分支网络。组装动力学可以很好地用 Smoluchowski 凝聚过程来描述，我们从分子模拟中提取了速率常数，这些速率常数不仅提供了对微观组装动力学的深入了解，还将我们的聚集预测外推到分子模拟无法达到的时间和长度尺度。本研究提供了对 DFAG-OPV3-GAFD 肽自发自组装的形态和动力学的新的分子水平理解，并建立了一种系统的粗粒化模型开发方法，用于探索和设计具有可调光电性质的π 共轭肽。
