title: Self-assembly of regenerated silk fibroin from random coil nanostructures to antiparallel β-sheet nanostructures.
abstract: In this work, we studied the effects of incubation concentration and time on the self-assembly behaviors of regenerated silk fibroin (RSF). Our results showed the assembly ways of RSF were concentration-dependent and there were four self-assembly ways of RSF: (i) At relatively low concentration (≤0.015%), RSF molecules assembled into protofilaments (random coil), and then the thickness decreased and the secondary conformation changed to antiparallel β-sheet; (ii) at the concentration of 0.015%, RSF molecules assembled into protofilaments (random coil), and then assembled into protofibrils (antiparallel β-sheet). The protofibrils experienced the appearance and disappearance of phase periodic intervals in turn; (iii) at the concentration of 0.03%, RSF molecules assembled into bead-like oligomers (random coil), and then assembled into protofibrils (antiparallel β-sheet), and finally the height and phase periodic intervals of RSF protofibrils disappeared in turn; and (iv) at the relatively high concentration (≥0.15%), RSF molecules assembled into protofilaments (random coil), then aggregated into blurry cuboid-like micelles (random coil), and finally self-arranged to form smooth and clear cuboid-like micelles (antiparallel β-sheet). These results provide useful insights into the process by which the RSF molecules self-assemble into protofilaments, protofibrils and micelles. Furthermore, our work will be beneficial to basic understanding of the nanoscale structure formations in different silk-based biomaterials.
authors.affiliation: National Engineering Research Center for Nanotechnology, Shanghai, 200241, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhong
authors.forename: Mengjia
authors.initials: M
authors.lastname: Ma
authors.forename: Wenying
authors.initials: W
authors.lastname: Li
authors.forename: Juan
authors.initials: J
authors.lastname: Zhou
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Yan
authors.forename: Dannong
authors.initials: D
authors.lastname: He
mesh_terms: D000818:Animals; D012831:Bombyx; D002942:Circular Dichroism; D005349:Fibroins / Q000737:chemistry* / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D005349:Fibroins
keywords: atomic force microscopy; micelle; molecular self-assembly; protofibril; protofilament; silk fibroin