Stretch-Induced Helical Conformations in Poly(l-lysine)/Hyaluronic Acid Multilayers

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• 作者：Sarah Zahouani ; Alain Chaumont ; Bernard Senger ; Fouzia Boulmedais ; Pierre Schaaf ; Loïc Jierry ; Philippe Lavalle
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 22, 2016
• 年：2016
• 卷：8
• 期：24
• 页码：14958-14965
• 全文大小：460K
• 年卷期：0
• ISSN：1944-8252

文摘

We investigate the effect of stretching on the secondary structure of cross-linked poly(l-lysine)/hyaluronic acid (PLL/HA) multilayers. We show that stretching these films induces changes in the secondary structure of PLL chains. Our results suggest that not only α- but also 3₁₀-helices might form in the film under stretching. Such 3₁₀-helices have never been observed for PLL so far. These changes of the secondary structure of PLL are reversible, i.e., when returning to the nonstretched state one recovers the initial film structure. Using molecular dynamics simulations of chains composed of 20 l-lysine residues (PLL20), we find that these chains never adopt a helical conformation in water. In contrast, when the end-to-end distance of the chains is restrained to values smaller than the mean end-to-end distance of free chains, a distance domain rarely explored by the free chains, helical conformations become accessible. Moreover, the formation of not only α- but also 3₁₀-helices is predicted by the simulations. These results suggest that the change of the end-to-end distance of PLL chains in the stretched film is at the origin of the helix formation.