Fig. 2: Biocompatible and fluid NPA2 coacervate is wet bioadhesive and resistant to digestive enzymes.
a Fluid NPA2 coacervate formed a durable adhesive coating on the medical nitrile glove. b NPA2 coacervate can glue two ribbons of porcine skin tissue together and hold the weight of the tissues. c Schematic of the lap-shear test to measure the adhesive energy (Gad). Scale bar: 10 mm. d, e The adhesion performance of NPA2 coacervate was much better than that of the controls. NPA2 coacervate showed adhesive energy (Gad) comparable with the previously reported values (around 2–10 J m−2) for nanoparticle-based adhesives and polymeric adhesives. n = 5 independent lap-shear tests per group. f The hydrogen-bonding interactions derived from catechol groups ensure the stable and reversible adhesion energy level of NPA2 coacervate during the successive bonding/debonding cycles. g The viability staining of human mesenchymal stem cells (hMSCs) also suggested excellent cytocompatibility of the NPA2 coacervate. Scale bar: 200 μm. h No significant differences in body weights were observed between the rats receiving oral administration of NPA2 coacervate on days 1, 3, 5, 7, and 9, and untreated healthy rats during the 10-day toxicity evaluation. n = 3 biologically independent rats in control group, n = 4 biologically independent rats in NPA2 group. i, j The fluid NPA2 coacervate coating (stained by Fast Green FCF) can adhere to the fresh and wet mucosa, flow down slowly, and remain stable after soaking in simulated gastric fluid (Ga) and simulated intestinal fluid (In) at 37 °C for 2 h, respectively. Scale bar: 15 mm. k, l GPC data of the fresh (Ga, In) and used simulated gastric or intestinal fluid (Ga′, In′) incubated with NPA2 coacervate. No degraded or dissolved NPA2 coacervate components were found in the simulated gastric or intestinal fluid, respectively. Data were presented as mean ± SD. ***p < 0.001 (Ordinary one-way ANOVA). Source data are provided as a Source Data file for Fig. 2d–f, h.
