Zhang Gong, Zhang Liwei, Rao Hengjun, Wang Yuefei, Li Qing, Qi Wei, Yang Xuejiao, Su Rongxin, He Zhimin
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China.
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China; Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin 300072, PR China.
J Colloid Interface Sci. 2020 Oct 1;577:388-396. doi: 10.1016/j.jcis.2020.05.087. Epub 2020 May 26.
We report the self-assembly of an ultra-pH-sensitive hydrogel from a simple dipeptide derivative, ferrocene-diphenylalanine (noted as Fc-FF). The pure Fc--Phe--Phe-OH (noted as (L)-Fc-FF) or Fc--Phe--Phe-OH (noted as (D)-Fc-FF) peptide could self-assemble into right- or left-handed nanohelices in a mixture of water and organic solvent leading to formation of stable chiral hydrogels at a very narrow pH range of 5.7-5.9. Intriguingly, if we used a racemic mixture (noted as (L,D)-Fc-FF) of (L)-Fc-FF and (D)-Fc-FF, stable hydrogels could only be formed at much lower pH values with a weak mechanical property. The results indicated that the molecular chirality has great influence on the gelation of the peptides. Moreover, we investigated the gelation behaviour of the peptides in various solvents. Here the water molecules are essential in directing the chiral self-assembly of Fc-FF into entangled chiral nanostructures, leading to the formation of stimuli-responsive hydrogels. And in the presence of water molecules, a small amount of organic co-solvents also has significant effect on the gelation of Fc-FF peptides. This work demonstrated that the gelation of such a bioorganometallic molecule is very sensitive to the molecular conformation of itself and the self-assembly environment (pH, solvents, etc.), which has potential applications in chemical sensing and biomedicine.
我们报道了一种由简单的二肽衍生物二茂铁 - 二苯基丙氨酸（记为Fc - FF）自组装形成的超pH敏感水凝胶。纯的Fc - Phe - Phe - OH（记为(L)-Fc - FF）或Fc - Phe - Phe - OH（记为(D)-Fc - FF）肽能在水和有机溶剂的混合物中自组装成右手或左手纳米螺旋，从而在5.7 - 5.9这一非常窄的pH范围内形成稳定的手性水凝胶。有趣的是，如果我们使用(L)-Fc - FF和(D)-Fc - FF的外消旋混合物（记为(L,D)-Fc - FF），则只能在低得多的pH值下形成稳定的水凝胶，且其机械性能较弱。结果表明分子手性对肽的凝胶化有很大影响。此外，我们研究了肽在各种溶剂中的凝胶化行为。在这里，水分子对于将Fc - FF的手性自组装引导成缠结的手性纳米结构至关重要，从而导致形成刺激响应性水凝胶。并且在有水分子存在的情况下，少量的有机共溶剂对Fc - FF肽的凝胶化也有显著影响。这项工作表明，这种生物有机金属分子的凝胶化对其自身的分子构象和自组装环境（pH、溶剂等）非常敏感，这在化学传感和生物医学方面具有潜在应用。
