Commercial or clinical
tissue adhesives are currently limited due
to their weak bonding strength on wet biological tissue surface, low
biological compatibility, and slow adhesion formation. Although catechol-modified
hyaluronic acid (HA) adhesives are developed, they suffer from limitations:
insufficient adhesiveness and overfast degradation, attributed to
low substitution of catechol groups. In this study, we demonstrate
a simple and efficient strategy to prepare mussel-inspired HA hydrogel
adhesives with improved degree of substitution of catechol groups.
Because of the significantly increased grafting ratio of catechol
groups, dopamine-conjugated dialdehyde–HA (DAHA) hydrogels
exhibit excellent tissue adhesion performance (i.e., adhesive strength
of 90.0 ± 6.7 kPa), which are significantly higher than those
found in dopamine-conjugated HA hydrogels (∼10 kPa), photo-cross-linkable
HA hydrogels (∼13 kPa), or commercially available fibrin glues
(2–40 kPa). At the same time, their maximum adhesion energy
is 384.6 ± 26.0 J m–2, which also is 40–400-fold,
2–40-fold, and ∼8-fold higher than those of the mussel-based
adhesive, cyanoacrylate, and fibrin glues, respectively. Moreover,
the hydrogels can gel rapidly within 60 s and have a tunable degradation
suitable for tissue regeneration. Together with their cytocompatibility
and good cell adhesion, they are promising materials as new biological
adhesives.