纤维
疏水效应
两亲性
动态光散射
化学
化学物理
氢键
溶剂
结晶学
自组装
散射
透射电子显微镜
聚合物
材料科学
纳米技术
有机化学
分子
纳米颗粒
共聚物
光学
物理
生物化学
作者
Alessandra Del Giudice,Axel Rüter,Nicolae Viorel Pavel,Luciano Galantini,Ulf Olsson
出处
期刊:Langmuir
[American Chemical Society]
日期:2020-06-28
卷期号:36 (29): 8451-8460
被引量:16
标识
DOI:10.1021/acs.langmuir.0c00876
摘要
Within the homologous series of amphiphilic peptides AnK, both A8K and A10K self-assemble in water to form twisted ribbon fibrils with lengths around 100 nm. The structure of the fibrils can be described in terms of twisted β-sheets extending in the direction of the fibrils, laminated to give a constant cross section of 4 nm by 8 nm. The finite width of the twisted ribbons can be reasonably explained within a simple thermodynamic model, considering a free energy penalty for the stretching of hydrogen bonds along the twisted β-sheets and an interfacial free energy gain for the lamination of the hydrophobic β-sheets. In this study, we characterize the self-assembly behavior of these peptides in nonaqueous solutions as a route to probe the role of hydrophobic interaction in fibril stabilization. Both peptides, in methanol and N,N-dimethylformamide, were found to form fibrillar aggregates with the same β-sheet structure as in water but with slightly smaller cross-sectional sizes. However, the gel-like texture, the slow relaxation in dynamic light scattering experiments, and a correlation peak in the small-angle X-ray scattering pattern highlighted enhanced interfibril interactions in the nonaqueous solvents in the same concentration range. This could be ascribed to a higher effective volume of the aggregates because of enhanced fibril growth and length, as suggested by light scattering and cryogenic transmission electron microscopy analyses. These effects can be discussed considering how the solvent properties affect the different energetic contributions (hydrophobic, electrostatic, and hydrogen bonding) to fibril formation. In the analyzed case, the decreased hydrogen bonding propensity of the nonaqueous solvents makes the hydrogen bond formation along the fibril a key driving force for peptide assembly, whereas it represents a nonrelevant contribution in water.
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