Hydrazide derivatives are known to display a wide range of biological properties including antimicrobial activities, hence making them desirable candidates for soft biomaterials. Herein, we report chiral supramolecular coassembled hydrogels obtained from two phenylalanine gelators (L/DPF and B2L/D) and two dicarbohydrazide molecules (pyridine-2,6-dicarbohydrazide (PDH) and (2,2′-bipyridine)-5,5′-dicarbohydrazide (BDH)) that exhibited enhanced mechanical properties, chirality modulation, and antimicrobial activity. Four lines of coassembled hydrogels were obtained (i.e., L/DPF–PDH, L/DPF–BDH, B2L/D–PDH, and B2L/D–BDH) through hydrogen bonding and π–π stacking with some level of an interpenetrating network, as revealed by the structural characterization analysis. Mechanical properties were significantly improved, especially in the case of hybrid gels involving BDH, with improved average elastic modulus (G′) values of 3430 and 3167 Pa for DPF–BDH and B2D–BDH (1:3, molar concentration) over 140 and 1680 Pa for DPF and B2D gelators, respectively. This was attributed to the improved π–π stacking and interpenetrating network due to the bipyridine group and its ease to form fibrous precipitates in the process of heating and cooling to room temperature. PDH, on the other hand, was able to modulate chirality in the L/DPF gelator due to its more planar and less bulky nature and showed antimicrobial activity against Pseudomonas aeruginosa (Gram-negative). Interestingly, when PDH was coassembled with the B2L/D gelator, the hybrid gels exhibited antimicrobial activity against Staphylococcus aureus (Gram-positive) and P. aeruginosa (Gram-negative) by virtue of a synergistic effect of the gelator and the azomethine group of PHD. Hence, by moving from bipyridine (BDH) to pyridine (PDH) as a core structure in the hydrazide molecules, the resulting hybrid hydrogels exhibited desirable properties of antimicrobial activity and improved mechanical attributes.

中文翻译：

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具有增强的机械性能的基于苯丙氨酸的手性共组装水凝胶的抗菌活性：吡啶肼衍生物的影响。

已知酰肼衍生物具有广泛的生物学特性，包括抗微生物活性，因此使其成为柔软生物材料的理想候选者。本文中，我们报道了从两个苯丙氨酸胶凝剂（L / DPF和B2L / D）和两个二碳酰肼分子（吡啶-2,6-二甲酰肼（PDH）和（2,2'-联吡啶）-5,5表现出增强的机械性能，手性调节和抗菌活性的'-二氢乙酰肼（BDH））。获得了四行共组装的水凝胶（即。，L / DPF–PDH，L / DPF–BDH，B2L / D–PDH和B2L / D–BDH）通过一定程度的互穿网络通过氢键和π–π堆叠，如结构表征分析所示。机械性能得到显着改善，尤其是在涉及BDH的杂化凝胶中，其平均弹性模量（G'）DPF-BDH和B2D-BDH胶凝剂的140和1680 Pa分别为3430和3167 Pa（摩尔浓度为1：3，摩尔浓度）。这归因于联吡啶基团改善了π-π堆叠和互穿网络，并且在加热和冷却至室温的过程中易于形成纤维状沉淀。另一方面，PDH能够调节L / DPF胶凝剂中的手性，因为它更具平面性且体积较小，并且对铜绿假单胞菌（革兰氏阴性）表现出抗菌活性。有趣的是，当PDH与B2L / D胶凝剂共同组装时，杂合凝胶显示出对金黄色葡萄球菌（革兰氏阳性）和铜绿假单胞菌的抗菌活性。（革兰氏阴性）凭借凝胶剂和PHD的甲亚胺基团的协同作用。因此，通过从联吡啶（BDH）移至吡啶（PDH）作为酰肼分子的核心结构，所得杂化水凝胶显示出所需的抗菌活性，并改善了机械性能。