Temperature-sensitive mussel-inspired citrate-based tissue adhesives with low-swelling

ABSTRACT Mussel-inspired tissue adhesives have been widely studied in recent years because of their excellent underwater adhesion. Our recent study has synthesized a series of tissue adhesives with citric acid, dopamine, 1,8-octanediol and poly(ethylene oxide) (PEO), and found that amphiphilic adhesives showed an efficient underwater adhesion mechanism. Poly(propylene oxide)-poly(ethylene oxide) block copolymer (PEO-PPO-PEO) is a thermosensitive amphiphilic material, widely used in medical field. Herein, we replaced PEO with PEO-PPO-PEO to introduce temperature-sensitivity into adhesives, and utilized the hydrophilic-to-hydrophobic transition of PEO-PPO-PEO to reduce the swelling at human temperature. Fortunately, we got positive results that all the synthetized adhesives showed obvious temperature-sensitivity. The transition from low temperature to room temperature of the high concentrated uncured adhesive dispersion made it potentially injectable. After crosslinking, the swelling ratio of cured adhesives showed a significant decrease from 4°C to 37°C. And all the swelling ratios under 37°C were low, ranging from 8.4% to 22.5%. Additionally, the lap-shear adhesion strength on wet porcine skin was in the range of 29.2–67.1 kPa, which was higher than that of commercial fibrin glue (9–15 kPa). By selecting different (PEO)y(PPO)x(PEO)y, we could obtain adhesives with wide mechanical properties and broaden the scope of use of the adhesives.