Fig. 6: Solidification process of the unfolded BSA glue and characteristics of the inner structure and surface chemistry of the solidified glue.
From: Synthesis of robust underwater glues from common proteins via unfolding-aggregating strategy
a Photograph of a round glass sheet (6 mm in diameter) that was used to analyze the solidification process of the unfolded BSA glue. The observation area is marked with a yellow box. The FE simulated results (b) and ThT staining fluorescence image (c) of the glue solidification between two glass slides after immersing in water for 10 min, and the width change of the solidified glue ring against time calculated from the above two methods (d). e Field emission SEM (FE-SEM) images of the highlighted section of the glue after solidification. The upper left region corresponds to the surface of the glue bonded to the glass slide, and the lower right region corresponds to the inner morphology of the solidified glue. f The ultrathin-section TEM image of the solidified glue in bulk. The light area is amorphous, and the black areas are nanocrystals. The corresponding selected area electron diffraction (SAED) patterns were displayed on the right. g Local magnification of the black area, and XRD pattern of the freeze-dried solidified glue (inset, Bruker D8 Advance, Cu target, wavelength = 0.154 nm). h Amino acid composition analysis on the surface of the solidified BSA glue as characterized by TOF-SIMS. Data are mean ± S.D. n = 3 independent samples per group. i Schematic of the solidified glue structure, where the green cuboid bulk represents the nanocrystalline region of β-sheet aggregation, and the blue curve represents the amorphous region. The experiments in (c, e–g) were repeated independently at least three times with similar results.
