Here, we report the synthesis and structural characterization of novel iron nanoparticles (FeNPs)-based short-peptide supramolecular hydrogels. These hybrid hydrogels composed of Fmoc-diphenylalanine (Fmoc-FF) peptide and FeNPs were prepared through the self-assembly of Fmoc-FF in a suspension containing FeNPs in the presence or absence of an external magnetic field. Optical images of these hydrogels revealed the formation of column-like aggregates of FeNPs when the gels were formed in the presence of a magnetic field. Moreover, the intricate structure derived from the interwoven nature of the fiber peptides with these FeNP column-like aggregates resulted in anisotropic materials, more rigid under shear forces applied perpendicularly to the direction of the aggregates, presenting under these conditions values of G′ (storage modulus) about 7 times those of the native hydrogel. To the best of our knowledge, this is the first example in which the mechanical properties of peptide hydrogels were strongly enhanced due to the presence of FeNPs. A theoretical model trying to explain this phenomenon is presented. Quite interesting CD, FTIR and synchrotron X-ray diffraction analyses indicated that the anti-parallel β-sheet arrangement of Fmoc-FF peptide was highly conserved in the hydrogels containing FeNPs. Moreover, FLCS measurements showed that the diffusion of a small solute through the hydrogel network was improved in hydrogels containing FeNPs, probably caused by the formation of preferential channels for diffusion. Taken together, our results provide a new method for the synthesis of novel hybrid Fmoc-FF–FeNPs anisotropic hydrogels with enhanced mechanical strength and water-like diffusion behavior, thus easing their application in drug delivery and tissue engineering.

中文翻译：

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基于铁纳米颗粒的超分子水凝胶可产生具有增强的机械强度的各向异性杂化材料†

在这里，我们报告基于新型铁纳米粒子（FeNPs）的短肽超分子水凝胶的合成和结构表征。由Fmoc-二苯丙氨酸（Fmoc-FF）肽和FeNPs组成的这些杂化水凝胶是通过在存在或不存在外部磁场的情况下，通过Fmoc-FF在含有FeNPs的悬浮液中的自组装而制备的。这些水凝胶的光学图像显示，当在磁场存在下形成凝胶时，会形成FeNP的柱状聚集体。此外，源自纤维肽与这些FeNP柱状聚集体的交织性质的复杂结构导致各向异性材料，在垂直于聚集体方向施加的剪切力下，刚性更高，在这些条件下呈现G''（储能模量）约为天然水凝胶的7倍。据我们所知，这是第一个因FeNPs的存在而使肽水凝胶的机械性能大大提高的例子。提出了试图解释这种现象的理论模型。非常有趣的CD，FTIR和同步加速器X射线衍射分析表明，Fmoc-FF肽的反平行β-折叠排列在含有FeNPs的水凝胶中高度保守。此外，FLCS测量表明，在含有FeNPs的水凝胶中，小溶质通过水凝胶网络的扩散得到了改善，这可能是由于形成了优先扩散通道所致。在一起