Injectable polyvinylpyrrolidone/tannic acid multifunctional hydrogel coating with excellent self-healing and adhesive properties for application in tissue engineering

Hydrogels can simulate the physiological environment of soft tissues, showing great promise in spinal cord injury (SCI) repair. Nevertheless, hydrogels for effective SCI repair have limitations such as their inability to effectively contact with irregular cavities and structural damage caused by long-term physical movement. In this study, a unique and facile hydrogel with injectable, electroconductive, self-healing, and adhesive properties was synthesized by introducing tannic acid (TA) and polyvinylpyrrolidone (PVP)-stabilized polypyrrole (PPy) nanoparticles. Fe(III) ion-triggered in situ polymerization of pyrrole, and the dispersibility of PPy was significantly improved utilizing the stabilizing effect of PVP. The P@Py/TA had excellent injectable, self-healing, and cytocompatibility properties. Meanwhile, the hydrogel coating exhibited robust self-adhesion to different substrates. The P@Py/TA provided a suitable microenvironment for axon regeneration, effective angiogenesis, and immune-regulated function. This facilitated functional recovery from traumatic SCI. The multifunctional conductive P@Py/TA hydrogel scaffold provides a new strategy for SCI repair and has potential applications in other fields of bionic skin and multi-functional coatings.