Assembly of whey protein nanofibrils into macroscopic filaments

Sammanfattning: Recently, it has been reported that the increasing number of plastic are significantly floated in the sea, because they are difficult to be degraded naturally. This lack of biodegradability requires us to develop new environmental-friendly material replacing current plastics. One promising composite of bio-friendly material is proteins, since there are abundant in our nature. Here, this study aims to exploit such proteins to form macroscopic fibers, which could open the new path to use of protein-based materials. We approach this in ‘bottom-up’ method, which means to combine the small pieces to develop large and complex materials. First, we made protein nanofibrils from native proteins, turning them from nanometer scale into microscopic scale. Subsequently, these nanofibrils are assembled into macrofibers, achieving macroscopic scale. Since the properties of final material are strongly depending on the assembly of thier building blocks, it is required to control the assembly system. We realize this with flow-focusing spinning setup, which enable to control the orientation of nanofibrils by the acceleration of the flow. We have tested some conditions of the nanofibrils, especially the morphology of fibrils such as flexible and straight fibrils, and identified essential parameters for the assembly of nanofibrils. These results give us not only the insight of complex assembly mechanism of proteins, but also the opportunity to develop the new protein-based material.