Self-Assembly of A尾-Based Peptide Amphiphiles with Double Hydrophobic Chains

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• 作者：Chengqian He ; Yuchun Han ; Yaxun Fan ; Manli Deng ; Yilin Wang
• 刊名：Langmuir
• 出版年：2012
• 出版时间：February 21, 2012
• 年：2012
• 卷：28
• 期：7
• 页码：3391-3396
• 全文大小：526K
• 年卷期：v.28,no.7(February 21, 2012)
• ISSN：1520-5827

文摘

Two peptide鈥揳mphiphiles (PAs), 2C₁₂鈥揕ys鈥揂尾(12鈥?7) and C₁₂鈥揂尾(11鈥?7)鈥揅₁₂, were constructed with two alkyl chains attached to a key fragment of amyloid 尾-peptide (A尾(11鈥?7)) at different positions. The two alkyl chains of 2C₁₂鈥揕ys鈥揂尾(12鈥?7) were attached to the same terminus of A尾(12鈥?7), while the two alkyl chains of C₁₂鈥揂尾(11鈥?7)鈥揅₁₂ were separately attached to each terminus of A尾(11鈥?7). The self-assembly behavior of both the PAs in aqueous solutions was studied at 25 掳C and at pHs 3.0, 4.5, 8.5, and 11.0, focusing on the effects of the attached positions of hydrophobic chains to A尾(11鈥?7) and the net charge quantity of the A尾(11鈥?7) headgroup. Cryogenic transmission electron microscopy and atomic force microscopy show that 2C₁₂鈥揕ys鈥揂尾(12鈥?7) self-assembles into long stable fibrils over the entire pH range, while C₁₂鈥揂尾(11鈥?7)鈥揅₁₂ forms short twisted ribbons and lamellae by adjusting pHs. The above fibrils, ribbons, and lamellae are generated by the lateral association of nanofibrils. Circular dichroism spectroscopy suggests the formation of 尾-sheet structure with twist and disorder to different extents in the aggregates of both the PAs. Some of the C₁₂鈥揂尾(11鈥?7)鈥揅₁₂ molecules adopt turn conformation with the weakly charged peptide sequence, and the Fourier transform infrared spectroscopy indicates that the turn content increases with the pH increase. This work provides additional basis for the manipulations of the PA鈥檚 nanostructures and will lead to the development of tunable nanostructure materials.