Figure 8. Methods and procedures for developing synthetic bioadhesives.

(A) Crosslinking mechanisms and the molecular interactions between the substrate leading to adhesion in nucleobase materials. (B) Demonstration of adhesion of polyphosphoesters to glass vials and (C) human skin. Reprinted with permission from ref ¹⁵². Copyright 2019 American Chemical Society. (D) Schematic of the tough hydrogels comprised of a dissipative layer matrix and bridging polymers containing primary amines, which can diffuse into the substrate and the sealant. Propagation of a crack at the tissue interface is inhibited by the energy absorbed through the dynamic ionic bonds between the calcium ions and alginate chains. (E) Illustration of the tough adhesive adhered to the myocardium tissue while peeling off, and (F) under internal pressure. Reprinted with permission from ref ¹⁵⁷. Copyright AAAS. (G) Schematic of the xylose-based polyurethane (PU) sealant and their mechanism of adhesion. Reprinted with permission from ref ¹⁷⁰. Copyright 2016 American Chemical Society. (H) Chemistry of adhesion in the polyethylene glycol (PEG)-lysozyme (LZM) hydrogels formed via the amidation reaction between the egg-derived lysozyme protein and 4-arm-PEG-N-hydroxysuccinimide. (I) Demonstration of the conformation of hydrogels onto the tissue under different deformation scenarios. (J) In vitro analysis of the burst tests on the porcine vessels, and (K) the burst pressure results showing that the strength values are greater than those of the normal arterial blood pressure. Reproduced with permission from ref ¹⁷. Copyright 2019, Elsevier. (L) Schematic of the composite fiber deposition on the wounded tissue using an airbrush acting as a surgical sealant. (M) Burst pressure data for the sealants show enhanced strength with increasing silica particle size in PEG/poly(lactic-co-glycolic acid) (PLGA)-based hydrogel. Reproduced with permission from ref ¹⁷⁶. Copyright 2019, Elsevier. N-hydroxysuccinimide, NHS.