Engineering multifunctional bioadhesive powders through dynamic metal-ligand coordination

Bioadhesive gels with robust adhesion on wet and irregular tissue surfaces are desirable for clinical applications. Assembly of bioadhesive powders is an effective strategy for obtaining gels that adhere to wet and irregular tissue surfaces by absorbing interfacial water. However, current bioadhesive powders lack positive biological functions and are prone to postoperative adhesion. Here, we present a powder strategy based on metal-ligand coordination to create a series of bioadhesive polyacrylic acid (PAA) gels. In the gel network, metal ions (Mn+) are used to coordinate with the carboxy ligands of PAA to form dynamic noncovalent crosslinks. The powders can absorb interfacial water and assemble into gels on wet and irregular tissue surfaces within a few seconds, forming an initial adhesion layer by electrostatic interactions. Furthermore, the polymers can diffuse into the tissue matrix, and metal-ligand coordination is reconstructed to enhance the adhesion. Moreover, with a cationic shield layer, the bioadhesive powders can effectively avoid postoperative adhesion. Importantly, ions endow the gel with customized biological functions. We demonstrate that the hemostatic, antibacterial, peroxidase-like catalytic, and photodetachment abilities of the gels by incorporating different Mn+ ions. These advantages make the bioadhesive powder a promising platform for diverse tissue repair applications.