Self-assembling cyclic peptide nanotubes are fascinating supramolecular systems with promising potential for various applications, such as drug delivery, transmembrane ionic channels, and artificial light-harvesting systems. In this study, we present novel pH-responsive nanotubes based on asymmetric cyclic peptide-polymer conjugates. The pH response is introduced by a tertiary amine-based polymer, poly(dimethylamino ethyl methacrylate) (pDMAEMA) or poly(diethylamino ethyl methacrylate) (pDEAEMA) which is quaternised at low pH. The self-assembling behaviour of their corresponding conjugates is investigated using different scattering and spectroscopy techniques. Compared to conjugates with hydrophilic polymeric corona, the introduction of hydrophobic polymer chains on the periphery of the cyclic peptides can prevent water molecules from penetrating through to the peptide rings, allowing the construction of hydrogen bonding interactions between cyclic peptides to form longer nanotubes. The switching between assembly and non-assembly is triggered by the change in the surrounding environmental pH, which process is controlled by the coordination between hydrophobic interactions and electrostatic repulsions. Due to the different hydrophobicity of these two polymers, the self-assembly of their corresponding conjugates varies extensively. We first demonstrate this evolution in detail and describe the relationship between the self-assembly and the inherent properties of grafted polymers, such as polymer compositions, the protonation degree of the responsive polymers and the polymer molecular weight in solutions.

中文翻译：

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来自不对称环状肽-聚合物偶联物的 pH 响应性纳米管


自组装环肽纳米管是令人着迷的超分子系统，在各种应用中具有广阔的潜力，例如药物递送、跨膜离子通道和人工光捕获系统。在这项研究中，我们提出了基于不对称环状肽-聚合物偶联物的新型 pH 响应纳米管。pH 响应由叔胺基聚合物、聚甲基丙烯酸二甲基氨基乙酯 （pDMAEMA） 或聚甲基丙烯酸二乙氨基乙酯 （pDEAEMA） 引入，其在低 pH 值下季铵化。使用不同的散射和光谱技术研究其相应偶联物的自组装行为。与亲水性聚合物电晕的偶联物相比，在环状肽的外围引入疏水性聚合物链可以防止水分子渗透到肽环，从而允许在环状肽之间构建氢键相互作用，从而形成更长的纳米管。组装和非组装之间的切换是由周围环境 pH 值的变化触发的，该过程由疏水相互作用和静电排斥之间的协调控制。由于这两种聚合物的疏水性不同，它们相应的偶联物的自组装变化很大。我们首先详细演示了这种演变，并描述了自组装与接枝聚合物的固有性质之间的关系，例如聚合物组成、响应聚合物的质子化度和溶液中的聚合物分子量。