Between Peptides and Bile Acids: Self-Assembly of Phenylalanine Substituted Cholic Acids

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• 作者：Leana Travaglini ; Andrea D鈥橝nnibale ; Maria Chiara di Gregorio ; Karin Schill茅n ; Ulf Olsson ; Simona Sennato ; Nicolae V. Pavel ; Luciano Galantini
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：August 8, 2013
• 年：2013
• 卷：117
• 期：31
• 页码：9248-9257
• 全文大小：597K
• 年卷期：v.117,no.31(August 8, 2013)
• ISSN：1520-5207

文摘

Biocompatible molecules that undergo self-assembly are of high importance in biological and medical applications of nanoscience. Peptides and bile acids are among the most investigated due to their ability to self-organize into many different, often stimuli-sensitive, supramolecular structures. With the aim of preparing molecules mixing the aggregation properties of bile acid and amino acid-based molecules, we report on the synthesis and self-association behavior of two diastereomers obtained by substituting a hydroxyl group of cholic acid with a l-phenylalanine residue. The obtained molecules are amphoteric, and we demonstrate that they show a pH-dependent self-assembly. Both molecules aggregate in globular micelles at high pH, whereas they form tubular superstructures under acid conditions. Unusual narrow nanotubes with outer and inner cross-section diameters of about 6 and 3 nm are formed by the derivatives. The diasteroisomer with 伪 orientation of the substituent forms in addition a wider tubule (17 nm cross-section diameter). The ability to pack in supramolecular tubules is explained in terms of a wedge-shaped bola-form structure of the derivatives. Parallel or antiparallel face-to-face dimers are hypothesized as fundamental building blocks for the formation of the narrow and wide nanotubes, respectively.