Recent advances in shear‐thinning and self‐healing hydrogels for biomedical applications

Abstract

Shear‐thinning and self‐healing hydrogels are being investigated in various biomedical applications including drug delivery, tissue engineering, and 3D bioprinting. Such hydrogels are formed through dynamic and reversible interactions between polymers or polypeptides that allow these shear‐thinning and self‐healing properties, including physical associations (e.g., hydrogen bonds, guest–host interactions, biorecognition motifs, hydrophobicity, electrostatics, and metal–ligand coordination) and dynamic covalent chemistry (e.g., Schiff base, oxime chemistry, disulfide bonds, and reversible Diels–Alder). Their shear‐thinning properties allow for injectability, as the hydrogel exhibits viscous flow under shear, and their self‐healing nature allows for stabilization when shear is removed. Hydrogels can be formulated as uniform polymer and polypeptide assemblies, as hydrogel nanocomposites, or in granular hydrogel form. This review focuses on recent advances in shear‐thinning and self‐healing hydrogels that are promising for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48668.

3D bioprinting of high cell-density heterogeneous tissue models through spheroid fusion within self-healing hydrogels

“…These results demonstrate that the shear-thinning and self-healing properties of support hydrogels allow spheroids to be freely moved within the hydrogel for patterning of multi-spheroid structures, without technically challenging intermediate layering and crosslinking steps. There are numerous shear-thinning and self-healing hydrogels that may be useful for this approach; however, these findings indicate that the hydrogel should be evaluated with respect to precision and cell viability prior to use 35 .…”

Injectables and Depots to Prolong Drug Action of Proteins and Peptides

“…These hydrogels become injectable under high mechanical shear and are capable of flowing through a needle, reforming their bonds and forming a cohesive depot at the injection site [ 312 ]. Their properties allow injection without needle occlusion, permitting homogenous encapsulation of a drug cargo and recovery of their initial state post-injection, making them suitable for the delivery of proteins [ 313 , 314 , 315 , 316 ]. It is essential that these hydrogels self-assemble at physiological conditions, flow freely through a syringe and self-heal after injection [ 272 , 312 ].…”

Self-healing and mechanical performance of dynamic glycol chitosan hydrogel nanocomposites

“…Recently, there has been growing interest in developing materials that are able to intrinsically self-heal after damage to recover their properties. 1,2 Despite the wide ranging application of hydrogels in fields such as biomedicine, 3 tissue engineering, 4,5 and batteries, 6 amongst others, their soft characteristics makes them susceptible to damage, such as macro-or microscale cracks that can be caused by mechanical or chemical factors. 7,8 To address these limitations, self-healing hydrogels have been developed that have the ability to extend the service life of these materials.…”