Robust Anisotropic Cellulose Hydrogels Fabricated via Strong Self-aggregation Forces for Cardiomyocytes Unidirectional Growth

Abstract

The development of a facile and fast method to construct anisotropic hydrogels with the ability to induce unidirectional growth of cells remains challenging. In this work, we demonstrated anisotropic cellulose hydrogels (ACHs) that are composed of nanoscale aligned nanofibers by dissolving cotton liner pulp in alkali/urea aqueous solution. On the basis of directionally controlling the architecture of cellulose chains with a facial prestretching strategy in chemical gel state and locking the highly ordered nanostructure through the formation of close physical networks via strong self-aggregation forces among neighboring cellulose nanofibers, ACHs, combing with a long-range aligned structure, entirely differential mechanical performances along the parallel and perpendicular directions of the hydrogel orientation and optical birefringence, were constructed. The aggregation of hydrogen bonds in anisotropic and isotropic hydrogels are of significant difference, confirmed by nuclear magnetic resonance technology. Importantly, ACHs with microgroove-like structure promote the adhesion and orientation of cardiomyocytes. Our work demonstrated the bottom-up fabrication of polysaccharide-based hydrogels with anisotropic structure and properties, paving the way to potentially apply them in cardiomyocytes in vitro culture system.

Switching between Elasticity and Plasticity by Network Strength Competition

“…More importantly, optical birefringence was observed to the deformed gel under polarized light, which further suggests the presence of oriented nanofibers (Figure C,F). The orientation of the embedded nanofibers could be resulted from the stretched polyacrylamide network following stretching as the two networks were intertwined and further interacted by hydrogen bonds . Additionally, the optical transmittance of the deformed gel decreased from 84% to 52% after further stretching, which could completely recover after unloading (Figure G,H).…”

“…A material, with a broad spectrum of mechanical property ranging from highly elastic to extremely plastic, would be ideal for many applications, but remains difficult . Although various strategies have been used either to improve the elasticity of polymer networks by crosslinking, phase separation, nanocomposite, etc., or to increase the plasticity with the assistance of plasticizers, blending, and supramolecular interactions, none of these can be accomplished in the same material . Methods capable of reversibly switching a material between elastic and plastic would be important.…”

“…The mechanical property including tensile and compressive strength in the perpendicular direction was much lower than that of the parallel direction, which could be explained by the lack of strong interactions between both the stretched polyacrylamide chains and the uniaxially aligned nanofibers. In contrast, the orientation of the embedded nanofibers and the stretched polyacrylamide network along the stretching direction endowed the hydrogels with much increased mechanical strength in the parallel direction . Given that many biological soft tissues, such as muscles, ligaments, and cartilage, exhibit various anisotropic mechanical properties that can meet different needs in complex environments, it is important to show that the mechanical anisotropy of synthetic hydrogels can be tuned .…”

Buckled Structures: Fabrication and Applications in Wearable Electronics

“…Prestretched anisotropic cellulose hydrogels that were synthesized by Zhang's group were subsequently released in sulfuric acid aqueous solution to remove solvent molecules from the hydrogels without reducing the elasticity. A relatively hard outside layer and a soft interdomain were created because of the difference between the speeds of solvent loss, thereby leading to wrinkled patterns along the perpendicular direction during the stress releasing process …”

Inorganic Salts Induce Thermally Reversible and Anti‐Freezing Cellulose Hydrogels

“…[16] Thetemperature-dependent properties of the cellulose hydrogels also inspired us to investigate their threedimensional (3D) printing processability.A se xpected, 3D printing can be easily realized ( Figure S1, Supporting Information). Ther emoldability is derived from the noncovalent cross-linking (mainly the hydrogen-bonding interactions and the metal-cellulose interactions).…”