Fig. 2
From: Femtosecond X-ray coherent diffraction of aligned amyloid fibrils on low background graphene
Preparation of TMV filaments and amyloid protofibrils on graphene. a, b Representative negative-stain TEM and AFM images of TMV, c–d bombesin filaments, and e, f β-endorphin filaments are shown. Negative-stain images (a, c, e) were acquired on fibrils placed on amorphous carbon films and AFM images (b, d, f) on graphene. Scalebars are 100 nm. b TMV fibrils align naturally on graphene over hundreds of nanometers. However, on the micrometer scale, aligned and randomly ordered fibrils are co-present. c Bombesin protofibrils associate laterally to form fibers, which randomly twist. A single preparation may consist of different polymorphs, e.g., twisted fibers and fibril rafts which are depicted here with arrows and squares, respectively. Bombesin fibers were mixed with TMV to compare their thickness. d The alignment of bombesin protofibrils on graphene is shown. Mature fibers are detected at larger magnifications. e β–endorphin protofibrils associate laterally to form twisted and striated fibers. f Aligned β–endorphin protofibrils were observed on graphene supports. To confirm that the features that are being imaged by the AFM are from the sample and not an artifact caused by the probe, the sample was rotated by 30° with respect to the scanning direction. Dashed circles represent the XFEL focus with FWHM = 150 nm
