hydrogels

Quantifying mechanical forces during vertebrate morphogenesis

Fig. 1 from : Eirini Maniou et al. 2024 “Quantifying mechanical forces during vertebrate morphogenesis”: The i3D bioprinting with accurately determined position, geometry and stiffness. a, Schematic of a chicken embryo illustrating the experimental workflow: 2–3 µl i3D polymer is pipetted directly onto the rhombocervical neuropore (RNP) and photo-crosslinked with a two-photon laser. The iMeSH structures are shown in green throughout. b, Stereoscope image of an embryo with a star shape photo- crosslinked on the flat neural plate. Scale bars, 200 µm. The star dimensions are indicated in the inset. c, Schematic showing iMeSH compression by apposition of the neural folds. d, Time-lapse images showing the sequential displacement of a rigid iMeSH shape, shown as a 3D confocal reconstruction superimposed on the embryo imaged with transmitted light. Cyan shading, open neural tube; *, zippering point; arrow indicates rotation of the printed shape; scale bar, 50 µm. The times are shown. e, Fire lookup table showing the autofluorescence of iMeSH photo-crosslinked with the indicated laser powers on the same embryo. Scale bar, 25 µm. f, Schematic illustration of AFM stiffness testing of an iMeSH shape; 3D reconstructions of the shape are shown superimposed on a dorsal and transverse schematic of the embryo. Scale bar, 100 µm. g, AFM quantification of iMeSH crosslinked on an embryo at the indicated laser powers. The values were calculated from AFM indentations performed at a rate of 0.5 μm s–1 and depths of 1 μm (30% 7-hydroxycoumarin-3-carboxylic acid (HCC) polyethylene glycol (PEG)) or 2 μm (15% PEG). The force–displacement curves were acquired using NANOSENSORS™ PointProbe® Plus PPP-CONTSCR silicon AFM probes with a typical spring constant of 0.2 N/m.

Morphogenesis requires embryonic cells to generate forces and perform mechanical work to shape their tissues. Incorrect functioning of these force fields can lead to congenital… Read More »Quantifying mechanical forces during vertebrate morphogenesis

Strong, tough, rapid-recovery, and fatigue-resistant hydrogels made of picot peptide fibres

Fig. 2 from Bin Xue et al. “Strong, tough, rapid-recovery, and fatigue-resistant hydrogels made of picot peptide fibres”: Characterisation of supramolecular and picot GK11 peptide fibres without and with metal Cu2+ coordination. a AFM images of the fibres formed by the self-assembly of GK11 in the absence (top) and presence (bottom) of Cu2+. The graphs below the images correspond to the diameter distributions of the fibres. Scale bar = 1 μm. b, c CD spectrum (b) and FT-IR spectroscopy (c) of the self-assembled GK11 peptide with (GK11/Cu2+) and without Cu2+ (GK11). d As for (a), but for picot fibres (top) and metal ion-clad picot fibres (bottom) formed by GK11 linked with polyacrylamide in the absence and presence of Cu2+. Scale bar = 1 μm. NANOSENSORS PointProbe Plus PPP-SEIHR AFM probes for soft tapping mode were used.

Hydrogels are promising soft materials as tissue engineering scaffolds, stretchable sensors, and soft robotics. * Yet, it remains challenging to develop synthetic hydrogels with mechanical… Read More »Strong, tough, rapid-recovery, and fatigue-resistant hydrogels made of picot peptide fibres