Averaged theoretical amide I response of collagen-like peptide for rotation around the main axis of the molecule.

<p>A) Amide I band response of a collagen-like peptide (ID: 1BKV) oriented (φ = 0°, θ = 0°,) plane (i.e. perpendicular to the ZY plane) rotated at different ω angles around the c-axis and its average response. B) Amide I band response of a collagen-like peptide (ID:1BKV) lying in the ZY plane (φ = 90°, θ = 0°) that has been rotated at different ω angles around the c-axis of the molecule and its average response. All graphs are plotted as functions of the polarization angle β of the incident laser beam (according to eq.3).</p

Global coordinate system and the Euler angles that describe the position of the molecular structures of collagen-like peptide and alpha helix.

<p>The directions of propagation of the incident and scattered beam (E_i and E_s) are represented by the red arrows parallel to the X axis while yellow bar represents the position of molecular structures. The “in plane” rotations are performed in the plane YZ and the “out of plane” rotations are performed in the ZX plane.</p

Averaged theoretical amide I response of collagen-like peptide molecules for “out of plane” rotation.

<p>Normalized amide I response for four different collagen-like peptide structures (ID: 1BKV, 1CGD, 1QSU) that are rotated in the plane XZ [from (φ = 90°, θ = 90°) to (φ = 0°, θ = 90°)] <i>vs</i> the polarization angle of the incident light. The responses have been averaged at angles ω = 0°, ω = 90°, ω = 180°, ω = 270°. All the molecules exhibit a similar trend independent from which collagen-like peptide crystal structure. The average responses for all the selected structures are marked in bold.</p

Shape-Programmed Folding of Stimuli-Responsive Polymer Bilayers

We investigated the folding of rectangular stimuli-responsive hydrogel-based polymer bilayers with different aspect ratios and relative thicknesses placed on a substrate. It was found that long-side rolling dominates at high aspect ratios (ratio of length to width) when the width is comparable to the circumference of the formed tubes, which corresponds to a small actuation strain. Rolling from all sides occurs for higher actuation, namely when the width and length considerably exceed the deformed circumference. In the case of moderate actuation, when both the width and length are comparable to the deformed circumference, diagonal rolling is observed. Short-side rolling was observed very rarely and in combination with diagonal rolling. On the basis of experimental observations, finite-element modeling and energetic considerations, we argued that bilayers placed on a substrate start to roll from corners due to quicker diffusion of water. Rolling from the long-side starts later but dominates at high aspect ratios, in agreement with energetic considerations. We have shown experimentally and by modeling that the main reasons causing a variety of rolling scenarios are (i) non-homogenous swelling due to the presence of the substrate and (ii) adhesion of the polymer to the substrate

<i>In situ</i> PRS mapping of the collagen orientation in −45 and 45 degrees tilted dried RTT.

<p>(A) and (C) show maps obtained by fitting thirteen Raman images collected with different polarization angles of the incident laser light. The direction of arrows indicates the orientation of collagen molecules, their length represents the amplitude of the fitting curve, and the color code is the average intensity of the amide I band. (B) and (D) are example of experimental points extracted from the area marked in (1) and (2), respectively.</p

Shape-Programmed Folding of Stimuli-Responsive Polymer Bilayers

We investigated the folding of rectangular stimuli-responsive hydrogel-based polymer bilayers with different aspect ratios and relative thicknesses placed on a substrate. It was found that long-side rolling dominates at high aspect ratios (ratio of length to width) when the width is comparable to the circumference of the formed tubes, which corresponds to a small actuation strain. Rolling from all sides occurs for higher actuation, namely when the width and length considerably exceed the deformed circumference. In the case of moderate actuation, when both the width and length are comparable to the deformed circumference, diagonal rolling is observed. Short-side rolling was observed very rarely and in combination with diagonal rolling. On the basis of experimental observations, finite-element modeling and energetic considerations, we argued that bilayers placed on a substrate start to roll from corners due to quicker diffusion of water. Rolling from the long-side starts later but dominates at high aspect ratios, in agreement with energetic considerations. We have shown experimentally and by modeling that the main reasons causing a variety of rolling scenarios are (i) non-homogenous swelling due to the presence of the substrate and (ii) adhesion of the polymer to the substrate

Polarized Raman spectroscopy of RTT.

<p>Spectra taken at the same spot of the sample were collected with two different laser polarization orientations [parallel (laser X, blue line) and perpendicular (laser Z, red line) to the tendon axis]. A large anisotropy of the amide I band in the two different laser to fiber configurations is due to the preferential orientation of vibrational units along the main axis of the tendon.</p

Theoretical prediction of the anisotropic response of amide I band for collagen-like and alpha helix molecules.

<p>Normalized anisotropic response of the amide I band of a collagen-like peptide molecule (ID:1CAG) and alpha helix (ID:1XQ8) located at A) (φ = 90°, θ = 0°,ω = 0°) on the plane ZY, B) (φ = 90°, θ = 90°, ω = 0°) on the plane ZY and C) (φ = 0°, θ = 0°,ω = 0°) on the plane ZX. For the collagen-like peptide structure located “in plane” (A and B) the maximum response of the amide I band is obtained when the polarization of the light is parallel to the molecule position, the opposite response is observed for the alpha helix. In the “out of plane” (C) response both structures give rise to a much more isotropic response of the amide I band.</p

Relation between the orientation of tubules and the resulting shapes and average spacing of tubule cross-sections.

<p>(a) Experimental observation under reflected light microscopy of a polished ivory section of the transverse plane, (b) Variation of the length of the cross-section of tubules depending on the cutting angle α, (c and d) 2D projections of the sectioned tubules with 0°< α < 90° of (c) the ordered cube where tubules are periodic and (d) the disordered cube where tubules are non-periodic. Average dot and line spacing are indicated in μm (line spacing = 120 μm/number of lines and dot spacing = √ (14400 μm²/number of dots) and (e) plot of the average dot spacing versus α.</p