Jellyfish-like structure that can mimic the swimming style of jellyfish is constructed with the PVA/GO nanocomposite hydrogel. More interestingly, the PVA/GO nanocomposite hydrogels exhibit pH-responsive mechanical properties, which become weaker when swollen in acidic and basic solutions. In addition, anisotropic tensile mechanical properties are also observed. The hydrogels exhibit high tensile and compressive strengths, up to 0.17 MPa and more than 2 MPa, respectively. The hydrogels show anisotropic porous structures consisted of microsized fibers and lamellae. Free-standing PVA/GO hydrogels with extremely high water contents (97–99 wt%) are obtained.
The resulting hydrogels show microstructures, water contents, and mechanical properties very similar to those of jellyfish mesogloea. Here we report the fabrication of a biomimetic jellyfish-like polyvinyl alcohol/graphene oxide (PVA/GO) nanocomposite hydrogel through a convenient and effective directional freezing–thawing technique. It remains a great challenge to fabricate hydrogels mimicking the hierarchical structures and intriguing properties of biological hydrogels. Jellyfish mesogloea with a well-developed anisotropic microstructure exhibits excellent and pH-responsive mechanical properties. These findings provide new perspectives on pore design principles toward future scaffolding of polymeric cross-linked matrices. The results demonstrate that the use of unidirectional freezing strongly increases the permeability of monolithic samples up to values usually required, for instance, in tissue engineering applications (higher than 2D).
However, the role of pore orientation on gas permeability was shown to be less marked as porosity increased. Compared to porous PEGDMA-based monoliths with non-aligned macropores, gas permeability was two to three times higher for oriented scaffolds at the same porosity level, a fact explained by the easier transport of gas molecules through the aligned structures. The influence of processing variables on the final properties of the materials was addressed, concerning particularly the effect of porosity and freezing directionality on air permeability. Porosities ranged between 80 and 95%, depending on the initial concentration of PEGDMA. Ice crystals were finally removed under vacuum producing macroporous hydrophilic networks with aligned pores. Solutions were vertically frozen in liquid nitrogen at a controlled rate to induce the oriented growth of ice crystals and then cryo-photopolymerized under blue-light irradiation. Scaffolds were obtained from aqueous solutions of a poly(ethylene glycol)dimethacrylate (PEGDMA) oligomer, a photosensitizer and a reducing agent. Unidirectional freezing followed by photopolymerization at subzero temperatures was used to obtain highly air-permeable monoliths with ordered porous structures. We discuss methods of creating high-quality alternatives to meat and dairy foods, describe their relative merits, and provide an outlook toward the future.Įxpected final online publication date for the Annual Review of Food Science and Technology, Volume 12 is March 2021. One can directly employ plant products, use intermediates such as cell factories, or grow cultured meat by using nutrients of plant origin. This review focuses on methods of creating an internal microstructure close to that of the animal-based originals. The best way to convince consumers to make this transition is to offer products that easily fit into their current habits and diets by mimicking the original foods. Because it will be impossible to supply sufficient protein to everyone solely with dairy and meat, we need to transition at least part of our diets toward protein foods that are more sustainable to produce. The increasing size and affluence of the global population have led to a rising demand for high-protein foods such as dairy and meat.
0 kommentar(er)
