(A) Ex vivo wound closure test using explanted rat aorta as a biological substrate for tissue adhesion. (i) An explanted aorta from a rat (about 4 cm in length). (ii) A patch generated using the MeTro hydrogel and wrapped the artery tube segments. The connecting anastomosis points were further glued with MeTro. Arrows present the rat artery and MeTro sealant. (iii) Adhesive strength of the MeTro sealant applied on one side (n = 4) and both sides (n = 3) of the artery in comparison with Evicel applied on one side (n = 4) and both sides (n = 4). The MeTro patch (n = 2) further improved the adhesive strength. (B) In vivo tests on rat arteries sealed by MeTro (n = 3). Operative sites (i) before and (ii) after sealing. White arrow presents the MeTro sealant on the artery. (iii) Image of a sealed artery pressurized with air, demonstrating that MeTro could adhere to the outer arterial surface and seal the incision, but the artery burst in another area. Circles present the MeTro seals. Arrow indicates bubbles from the burst point on the artery instead of the MeTro sealing site. (iv) Burst pressure values of artery sealed by MeTro with 20% concentration and high methacryloyl substitution after 4 days compared to a healthy artery as a control. Representative SEM (C) and H&E-stained (D) images from the interface between the explanted rat artery and the MeTro sealant. Tight interfaces between the MeTro hydrogel and the tissues indicate strong bonding and interlocking at the interfaces. Data are means ± SD. P values were determined by one-way ANOVA followed by Tukey’s multiple comparisons test for (A) and (B) (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).