Development of a Layered Hydrogel Inspired by the Layers of Natural Skin

Like biological tissue, hydrogels are crosslinked polymer networks capable of absorbing and retaining a high volume of water, and so are a promising scaffold material for mimicking the natural function of the body. However, the ability of current hydrogels to fully replicate the properties of natural tissue, including its strength and flexibility, is limited. The aim of this work was to prepare a gel that exhibits a stress-strain relationship like that of human skin. Methacrylic acid and oligo(ethylene glycol)methacrylate were copolymerized using reverse addition fragmentation chain transfer polymerization with differing monomer feed ratios. The resulting polymers were further modified via esterification with 4-hydroxybenzaldehyde before subsequent crosslinking using ethylenediamine at varying molar ratios. The resulting hydrogels possessed reversible dynamic bonds which gave the material good mechanical properties and self-healing ability. The layered biomimetic approach provided a greater overall improvement in mechanical properties compared to the single crosslinked polymer system, making it an attractive strategy for the development of high-performance biomaterials for applications where mechanical resilience and durability are vital.