Fibril Formation by pH and Temperature Responsive Silk-Elastin Block Copolymers

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• 作者：Monika D. Golinska ; Thao T. H. Pham ; Marc W. T. Werten ; Frits A. de Wolf ; Martien A. Cohen Stuart ; Jasper van der Gucht
• 刊名：Biomacromolecules
• 出版年：2013
• 出版时间：January 14, 2013
• 年：2013
• 卷：14
• 期：1
• 页码：48-55
• 全文大小：572K
• 年卷期：v.14,no.1(January 14, 2013)
• ISSN：1526-4602

文摘

In this report, we study the self-assembly of two silk-elastin-like proteins: one is a diblock S₂₄E₄₀ composed of 24 silk-like (S) repeats and 40 elastin-like (E) repeats; the other is a triblock S₁₂C₄E₄₀, in which the S and E blocks are separated by a random coil block (C₄). Upon lowering the pH, the acidic silk-like blocks fold and self-assemble into fibrils by a nucleation-and-growth process. While silk-like polymers without elastin-like blocks form fibrils by heterogeneous nucleation, leading to monodisperse populations, the elastin-like blocks allow for homogeneous nucleation, which gives rise to polydisperse length distributions, as well as a concentration-dependent fibril length. Moreover, the elastin-like blocks introduce temperature sensitivity: at high temperature, the fibrils become sticky and tend to bundle and aggregate in an irreversible manner. Concentrated solutions of S₁₂C₄E₄₀ form weak gels at low pH that irreversibly lose elasticity in temperature cycling; this is also attributed to fibril aggregation.