Robust-adhesion and high-mechanical strength hydrogel for efficient wet tissue adhesion†

Bioadhesive hydrogels show great promise in wound closure due to their minimally invasive nature and ease of use. However, they typically exhibit poor wet adhesion and mechanical properties on wet tissues. Herein, a ready-to-use bioadhesive hydrogel (denoted as PAA-NHS/C-CS) with rapidly robust adhesion and high mechanical strength is developed via a simple one-pot UV crosslinking polymerization of acrylic acid (AA), catechol-functionalized chitosan (C-CS), and acrylic acid N-hydroxysuccinimide ester (AA-NHS ester). Benefitting from the hydrogen bonds and electrostatic attractions formed between PAA-NHS and C-CS, the as-prepared hydrogel exhibits high tensile strength (∼630 kPa), fracture strain (∼1950%), and toughness (∼4250 kJ m⁻³) in the fully swollen state. Besides, the noncovalent interactions and covalent crosslinking formed between the dual adhesive moieties (the NHS ester and catechol groups) and the tissue surface endow the hydrogel with high shear strength (∼160 kPa), interfacial toughness (∼630 J m⁻²), and burst pressure (∼447 mmHg) on wet porcine skin. By integrating the high mechanical properties, rapid robust adhesion, and operational convenience, the as-prepared PAA-NHS/C-CS hydrogel shows great promise in wound closure.