National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, People's Republic of China.
Acta Biomater. 2013 Aug;9(8):7806-13. doi: 10.1016/j.actbio.2013.04.033. Epub 2013 Apr 27.
Silk fiber is one of the strongest and toughest biological materials with hierarchical structures, where nanofibril with size <20nm is a critical factor in determining its excellent mechanical properties. Although silk nanofibrils have been found in natural and regenerated silk solutions, there is no way to actively control nanofibril formation in aqueous solution. This study shows a simple but effective method of preparing silk nanofibrils by regulating the silk self-assembly process. Through a repeated drying-dissolving process, a silk fibroin solution composed of metastable nanoparticles was first prepared and then used to reassemble nanofibrils with different sizes and secondary conformations under various temperatures and concentrations. These nanofibrils have a similar size to that of natural fibers, providing a suitable unit to further assemble the hierarchical structure in vitro. Several important issues, such as the relationships between silk nanofibrils, secondary conformations and viscosity, are also investigated, giving a new insight into the self-assembly process. In summary, besides rebuilding silk nanofibrils in aqueous solution, this study provides an important model for furthering the understanding of silk structures, properties and forming mechanisms, making it possible to regenerate silk materials with exceptional properties in the future.
蚕丝纤维是具有分层结构的最强韧的生物材料之一，其中尺寸<20nm 的纳米原纤维是决定其优异机械性能的关键因素。尽管已经在天然和再生丝溶液中发现了丝纳米原纤维，但在水溶液中无法主动控制纳米原纤维的形成。本研究展示了一种通过调节丝自组装过程来制备丝纳米原纤维的简单而有效的方法。通过反复的干燥-溶解过程，首先制备了由亚稳纳米颗粒组成的丝素蛋白溶液，然后在不同温度和浓度下重新组装具有不同尺寸和二级构象的纳米原纤维。这些纳米原纤维的尺寸与天然纤维相似，为进一步体外组装分层结构提供了合适的单元。还研究了几个重要问题，例如丝纳米原纤维、二级构象和粘度之间的关系，为自组装过程提供了新的见解。总之，除了在水溶液中重建丝纳米原纤维外，本研究还为进一步了解丝结构、性能和形成机制提供了一个重要模型，使未来有可能再生具有特殊性能的丝材料。
