Fig. 2: Characterization of tissue adhesion and mIPN.

a Adhesion energy in the T-peel setup of the double-layered hydrogel patches after application to porcine small intestine, stom-ach and colon and corresponding PNHEA backing adhesion energies. n = 3 (independent ex-periments). Data shown as mean ± standard deviation. b Representative tensile strength curves of individual and fully assembled components of the hydrogel sealant. c Tensile stress of different components of the layered hydrogel system and stress modulation of PNAGA mIPN following incubation in various biological fluids. n = 3 (independent experiments). Data shown as mean ± standard deviation. d Assessment of the mutually interpenetrating network charac-ter by vibrational spectroscopy. Sampling locations are indicated in red rectangles. e FTIR measurements (location ①) indicating PNAGA traversing in the PAMPS layer by comparison of PAMPS support as prepared and PAMPS support side after mIPN attachment. Dotted lines indicate 1039 cm-1 (S-O), 1183 cm-1(PAMPS characteristic peak), 1557 cm-1, 1633 cm-1 char-acteristic amide peaks of PNAGA35. f Raman spectromicroscopy (location ②) and corre-sponding k-means clustering maps and spectra of histological sections of patch sealed small porcine intestine. Peak maps of the phenylalanine peak (1003 cm⁻¹) unique to tissue and a PNAGA peak (860 cm⁻¹) unique to the mIPN are displayed along with cluster 1 (biological tis-sue, in blue), cluster 2 PNAGA mIPN (polymer-rich, in red), and the overlay. Map of native in-testine (location ③, overlayed tissue cluster in blue, substrate cluster in green). Corresponding Raman spectra of the different clusters and pure materials (PNAGA mIPN, PAMPS support and PHEA backing) for reference. Figure wide color coding: intense red—fully applied patch using PNAGA mIPN, orange—PNAGA mIPN, red shading—PNAGA mIPN under different biological fluids, dark blue—non-adhesive backing, light blue—PAMPS adhesive support. Figure 2a, d has been created using biorender.com.