Institute of Applied and Computational Mathematics (IACM), Foundation for Research and Technology Hellas, (FORTH), IACM/FORTH, GR-71110 Heraklion, Greece.
Phys Chem Chem Phys. 2020 Dec 16;22(47):27645-27657. doi: 10.1039/d0cp03671d.
The self-assembly of diphenylalanine peptides (FF) on a graphene layer, in aqueous solution, is investigated, through all atom molecular dynamics simulations. Two interfacial systems are studied, with different concentrations of dipeptides and the results are compared with an aqueous solution of FF at room temperature. Corresponding length and time scales of the formed structures are quantified providing important insight into the adsorption mechanism of FF onto the graphene surface. A hierarchical formation of FF structures is observed involving two sequential processes: first, a stabilized interfacial layer of dipeptides onto the graphene surface is formulated, which next is followed by the development of a structure of self-aggregated dipeptides on top of this layer. The whole procedure is completed in almost 200 ns, whereas self-assembly in the system without graphene is accomplished much faster; in less than 50 ns cylindrical structures, the microscopic signal of the macroscopic fibrillar ones, are formed. Strong π-π* interactions between FF and the graphene lead to a parallel orientation to the graphene layer of the phenyl rings within a characteristic time of 80 ns, similar to the one indicated by the time evolution of the number of adsorbed FF atoms at the surface. Reduction in the number of hydrogen bonds between FF peptides is observed because of the graphene layer, since it disturbs their self-assembly propensity. The self-assembly of dipeptides and their adsorption onto the graphene surface destruct the hydrogen bond network of water, in the vicinity of FF, however, the total number of hydrogen bonds in all systems increases, promoting the formed structures.
通过全原子分子动力学模拟研究了苯丙氨酸二肽（FF）在水溶液中于石墨烯层上的自组装。研究了两种界面体系，具有不同浓度的二肽，并将结果与室温下 FF 的水溶液进行了比较。对形成的结构的相应长度和时间尺度进行了量化，为 FF 吸附到石墨烯表面的机制提供了重要的见解。观察到 FF 结构的分层形成，涉及两个连续的过程：首先，在石墨烯表面上形成稳定的二肽界面层，接着在该层上形成自聚集二肽的结构。整个过程在近 200 ns 内完成，而没有石墨烯的系统中的自组装则快得多；在不到 50 ns 的时间内，形成了圆柱形结构，这是宏观纤维状结构的微观信号。FF 与石墨烯之间的强 π-π*相互作用导致苯环在 80 ns 的特征时间内平行于石墨烯层取向，与表面上吸附的 FF 原子数量的时间演化所指示的时间相似。由于石墨烯层的存在，FF 肽之间的氢键数量减少，因为它干扰了它们的自组装倾向。二肽的自组装及其在石墨烯表面上的吸附破坏了 FF 附近水的氢键网络，然而，所有系统中的氢键总数增加，促进了形成的结构。
