Advanced dynamically crosslinked hydrogels: From design to human activity sensing and wound monitoring

Dynamically crosslinked hydrogels (DCHs) are networks of highly hydrated materials crosslinked with reversible dynamic bonds. These dynamic bonds break and rebuild in response to external stimuli or through their own intrinsic characteristics, providing the hydrogels with adaptive properties. Compared with conventional hydrogels, a key design principle emerging from DCHs is the strategic incorporation of reversible dynamic crosslinks that enable network reconfiguration and energy dissipation, thereby achieving a balance among self-healing, stimuli-responsiveness, and mechanical tunability. In this review, the preparation methods of DCHs have been categorized and discussed according to their dynamic crosslinking mechanism: dynamic non-covalent bonds (hydrogen bonds, host-guest interactions, ionic metal-ligand coordination interactions, and hydrophobic interactions), dynamic covalent bonds (Schiff-base bonds, Diels-Alder bonds, disulfide bonds, and boronate ester bonds), and multiple dynamic bonds. Subsequently, the relationship between the crosslinked structure and intelligent features of DCHs is also discussed. Next, we summarize the advanced DCHs for biomedical applications, especially in human activity sensing and wound healing monitoring. Finally, the limitations and prospects of DCHs are discussed.