Chau Ying, Luo Ying, Cheung Alex C Y, Nagai Yusuke, Zhang Shuguang, Kobler James B, Zeitels Steven M, Langer Robert
Department of Chemical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Biomaterials. 2008 Apr;29(11):1713-9. doi: 10.1016/j.biomaterials.2007.11.046. Epub 2008 Jan 14.
Controlling and guiding cell behavior requires scaffolding materials capable of programming the three-dimensional (3-D) extracellular environment. In this study, we devised a new self-assembling peptide template for synthesizing nanofibrous hydrogels containing cell-responsive ligands. In particular, the insertion of a matrix metalloproteinase-2 (MMP-2) labile hexapeptide into the self-assembling building blocks of arginine-alanine-aspartate-alanine (RADA) was investigated. A series of peptides, varied by the position of the MMP-2 hexapeptide substrate and the length of RADA blocks, were prepared by parallel synthesis. Their self-assembling capabilities were characterized and compared by circular dichroism spectroscopy and dynamical mechanical analysis. Among all the different insertion patterns, the sequence comprising a centrically positioned MMP-2 substrate was flanked with three RADA units on each side self-assembled into a hydrogel matrix, with mechanical properties and nanofiber morphology comparable to the native material built with (RADA)(4) alone. Exposure of the new gel to MMP-2 resulted in peptide cleavage, as confirmed by mass spectroscopy, and a decrease in surface hardness, as detected by nanoindentor, indicating that the enzyme mediated degradation was localized to the gel surface. The new design can be used for introducing biological functions into self-assembling peptides to create scaffolding materials with potential applications in areas such as tissue engineering and regenerative medicine.
控制和引导细胞行为需要能够对三维（3-D）细胞外环境进行编程的支架材料。在本研究中，我们设计了一种新的自组装肽模板，用于合成含有细胞反应性配体的纳米纤维水凝胶。特别地，研究了将基质金属蛋白酶-2（MMP-2）不稳定六肽插入精氨酸-丙氨酸-天冬氨酸-丙氨酸（RADA）的自组装结构单元中。通过平行合成制备了一系列肽，这些肽因MMP-2六肽底物的位置和RADA片段的长度不同而有所变化。通过圆二色光谱和动态力学分析对它们的自组装能力进行了表征和比较。在所有不同的插入模式中，包含位于中心位置的MMP-2底物且两侧各有三个RADA单元的序列自组装成水凝胶基质，其力学性能和纳米纤维形态与仅由（RADA）4构建的天然材料相当。质谱证实，将新凝胶暴露于MMP-2会导致肽裂解，纳米压痕仪检测到表面硬度降低，这表明酶介导的降解局限于凝胶表面。这种新设计可用于将生物学功能引入自组装肽中，以创建在组织工程和再生医学等领域具有潜在应用的支架材料。
