Microtubes with Rectangular Cross-Section by Self-Assembly of a Short β‑Peptide Foldamer

In nature, complex and well-defined structures are constructed by the self-assembly of biomolecules. It has been shown that β-peptide foldamers can mimic natural peptides and self-assemble into three-dimensional molecular architectures thanks to their rigid and predictable helical conformation in solution. Using shorter foldamers, which can be prepared more easily than longer ones, to form such architectures is highly desirable, but shorter foldamers have been overlooked due to the seemingly inferior number of intramolecular hydrogen bonds to stabilize a folded state in solution. Here we report that a β-peptide tetramer, although it lacks full helical propensity in solution, does self-assemble to form well-defined microtubes with rectangular cross-section by evaporation-induced self-assembly.自然界中，复杂且结构规整的分子结构由生物分子的自组装过程构建而成。已有研究证实，β-肽折叠体（β-peptide foldamers）可模拟天然肽，因其在溶液中具备刚性且可预测的螺旋构象，能够自组装形成三维分子架构。尽管短链折叠体相较于长链折叠体更易于合成，利用其构建此类分子架构是极具研究价值的方向，但由于溶液中稳定折叠构象所需的分子内氢键数量看似更少，短链折叠体长期以来被学界忽视。本研究报道，一种β-肽四聚体尽管在溶液中螺旋倾向性不足，但可通过蒸发诱导自组装（evaporation-induced self-assembly）过程，自组装形成具有规整矩形截面的微管。