A Multifunctional Adhesive Hydrogel with Antibacterial and Antioxidant Properties for Biointerface Applications

Poly(lipoic acid) (PLA) often suffers from poor stability in physiological environments and limited adhesion, which restricts its practical use. To address these issues, a multicomponent adhesive hydrogel was constructed by integrating sodium lipoate (LANa) and tannic acid (TA) into the system. LANa helps adjust the hydrophilicity of the network, while TA, with abundant phenolic groups, establishes extensive hydrogen-bonding interactions with the polydisulfide chains. These combined effects effectively inhibit disulfide bond cleavage and enhance the overall stability of the material. At the same time, the disruption of crystalline domains leads to a more amorphous structure, giving the hydrogel improved transparency, self-healing behavior, and resistance to repeated deformation. With the introduction of catechol/pyrogallol groups from TA, the hydrogel shows strong adhesion under wet conditions (up to 289 kPa on porcine skin) and can bond to a wide range of substrates. It also demonstrates notable biofunctionality, including efficient ROS scavenging (∼92%), high antibacterial activity (>98%), and low hemolysis (0.77%). In addition, the stable ionic conductivity and mechanical flexibility enable its use as a strain sensor for monitoring human motion. Overall, this study provides a feasible strategy for enhancing the stability and functionality of PLA-based hydrogels, suggesting their applicability in biomedical adhesives and flexible electronic devices.