Self-healing β-cyclodextrin/hyaluronic acid hydrogel with enhanced strength and self-healing efficiency

Hyaluronic acid (HA) self-healing hydrogels commonly suffer from an imbalance between mechanical properties and self-healing efficiency. To address this issue, we introduce carboxymethyl-β-cyclodextrin (β-CD) into the HA hydrogel system, which provides multiple crosslinking sites via β-CD's cyclic structure to improve its self-healing capability. The β-cyclodextrin/hyaluronic acid (ACD) hydrogels were prepared through dynamic acylhydrazone bond formation between aldehyde-modified HA (AHA) and hydrazide-modified carboxymethyl-β-cyclodextrin (β-CDD). Compared to aldehyde-modified HA/3,3'-dithiobis (propionyl hydrazide) (AHA/DTP, AD) hydrogels (~0.17 MPa), ACD hydrogels exhibited enhanced compressive strength of ~0.29 MPa, which was attributed to multiple interactions, such as dynamic covalent acylhydrazone bonds, hydrogen bonds, and physical filling. Furthermore, ACD hydrogels achieved 100 % healing efficiency in Young's modulus within 10 min, significantly higher than AD hydrogel (80 %) due to synergistic effects of dynamic covalent bonds, including acylhydrazone and disulfide bonds and hydrogen bonds. This hydrogel holds potential for various biomedical applications.