Reversible helical unwinding transition of a self-assembling peptide amphiphile

Tuning Self-Assembled Nanostructures Through Enzymatic Degradation of a Peptide Amphiphile

“…A series of off-axis reflections close to the equator are due to the helical twisting of nanoribbons. 22 The XRD pattern shows a high degree of alignment and multiple Bragg peaks confirming the regular ordering of the PA within the nanotubes/ribbons. In contrast, the XRD patterns for C 16 -KKF and C 16 -KKFF do not show orientation, and only present a small number of reflections.…”

“…20,21 The spectrum for C 16 -KKFFVLK is dominated by electronic transitions associated with the π–π stacking of the F residues, as discussed elsewhere. 22 The expected 23 CD spectrum for β-sheet structures, with a negative minimum near 216 nm and a positive maximum in the 195–202 nm range, is masked by these features. We provide evidence in a recent paper 22 that this PA does form β-sheet fibrils and this is supported by further data provided herein, to be discussed shortly.…”

Shape selection and multi-stability in helical ribbons

“…20,21 Helical structures also play a key role in engineering programmable matter 22 that exhibits a variety of geometries and functionality in a delicately controlled fashion, and in such emerging stimulated by their applications in nanoelecromechanical systems (NEMS), 23 active materials, 24,25 graphene materials, 26,27 drug delivery, 28 morphing structures in aerospace engineering, 30 optoelectronics, 31 and microrobotics. 32 Typically, helical ribbons result from the balancing of surface/residual stress with restoring forces of bending and stretching.…”

“…For example, peptides organized as bilayer membranes 38 form ribbons that coil into micron-long nanotubes, [39][40][41] and can transition reversibly between a purely twisted shape and a nanotube upon healing and cooling. 28 Moreover, the shape transition between twisted ribbons, two-dimensional disks, and double/triple helices can occur in colloidal membranes with the line tension tuned by molecular chirality. 29 Driven by mechanical anisotropy 42 and geometric misorientation, helical shapes form spontaneously, and the transitions between helicoids, cylindrical helical ribbons, general helical ribbons, and tubules can be achieved by tuning few geometric parameters such as the principal curvatures and mis-orientation angle.…”

Self-Assembly of Peptide Bioconjugates: Selected Recent Research Highlights

“…74 The parent PA self-assembles into helically twisted ribbons (and nanotubes), 75 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 21 C 16 -KKFF form small spherical micelles. 74 The enzyme elastase can be used to break up hydrogels formed by the self-assembly of the model surfactant-like alanine-rich peptide KA 6 E, which forms hydrogels containing tape-like fibrils.…”