Shanghai Synchrotron Radiation Facility, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
Nanoscale. 2019 Apr 25;11(17):8210-8218. doi: 10.1039/c9nr01092k.
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.
在纳米尺度受限的几何形状中，水具有与体相水不同的独特物理化学性质，尽管文献中提供的直接信息较少，但人们认为它在生物过程中发挥着重要作用。在这里，我们基于原子力显微镜（AFM）成像和分子动力学（MD）模拟，报道了一种称为 GAV-9 的神经退行性疾病相关肽在云母-石墨烯纳米毛细管中自组装的行为，该肽与在环境条件下浓缩的水纳米膜相互作用。结果表明，随着湿度的增加，GAV-9 肽单体吸附受限的水分子并转变成意想不到的水凝胶状结构。我们的 MD 模拟还表明，在受限的云母-石墨烯纳米毛细管中，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纤维。发现受限在云母-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，受限水层的分布在很大程度上取决于预先形成的肽纳米纤维的位置，并且随着水层的增加，肽纳米纤维进一步组装成纳米片，但随着水层的减少，肽纳米纤维解聚成无定形的肽组装体。肽纳米纤维的聚合和解聚可以以可逆的方式进行控制。我们的结果提供了一个简化的模型系统，以揭示受限界面水对分子水平上生物过程的影响。
