Assembly of peptides in mica-graphene nanocapillaries controlled by confined water
Assembly of peptides in mica-graphene nanocapillaries controlled by confined water
复制标题
受限水控制的云母-石墨烯纳米毛细管中肽的组装
作者：
Zhang Jinjin;Zhou Limin;Du Qiqige;Shen Zhiwei;Hu Jun;Zhang Yi
水在纳米尺度限制的几何形状具有独特的物理化学性质相比，散装水，并被认为在生物过程中发挥重要作用，虽然有较少的直接信息在文献中。在这里，我们报告的自组装行为的神经退行性疾病相关的肽称为GAV-9封装在云母-石墨烯纳米胶囊与水纳米膜在环境条件下凝聚的相互作用，基于原子力显微镜（AFM）成像和分子动力学（MD）模拟。结果显示，在湿度增加时，GAV-9肽单体吸附受限的水分子并转变为意想不到的水凝胶样结构。我们的MD模拟还表明，在受限的云母-石墨烯纳米胶囊中，GAV-9肽单体确实会形成富含水的水凝胶结构，而不是高度有序的纳米丝。发现限制在云母-石墨烯纳米毛细管中的界面水对于这种转变至关重要。此外，封闭水层的分布很大程度上取决于预先形成的肽纳米丝的位置，随着水层的增加，肽纳米丝进一步组装成纳米片，随着水层的减少，肽纳米丝解聚成无定形肽组装体。可以以可逆的方式控制肽纳米丝的聚合和解聚。我们的研究结果提供了一个简化的模型系统，揭示了封闭的界面水对生物过程的影响在分子水平上。
Water in nanoscale-confined geometries has unique physicochemical properties in contrast to bulk water, and is believed to play important roles in biological processes although there is less direct information available in the literature. Here, we report the self-assembly behaviors of a neurodegenerative disease related peptide termed GAV-9 encapsulated in mica–graphene nanocapillaries interacting with water nanofilms condensed under ambient conditions, based on atomic force microscopy (AFM) imaging and molecular dynamics (MD) simulations. The results revealed that, upon increase in the humidity, the GAV-9 peptide monomers adsorbed the confined water molecules and transitioned to unexpected hydrogel-like structures. Our MD simulations also suggested that in the confined mica–graphene nanocapillaries, the GAV-9 peptide monomers would indeed form water-rich hydrogel structures instead of highly ordered nanofilaments. The interfacial water confined in the mica–graphene nanocapillary is found to be crucial for such a transition. Moreover, the distribution of confined water layers largely depended on the locations of the preformed peptide nanofilaments, and the peptide nanofilaments further assembled into nanosheets with the water layer increasing, but depolymerized to amorphous peptide assemblies with the water layer decreasing. The polymerization and depolymerization of the peptide nanofilaments could be controlled in a reversible manner. Our results have supplied a simplified model system to uncover the effects of the confined interfacial water on the biological process at the molecular level.