Bioinspired lignin-based coatings for durable and photothermal antibacterial surfaces

Infection control remains a critical challenge in medical and environmental settings, intensified by the global rise of multidrug-resistant bacteria and the waning efficacy of conventional antibiotics. This study presents a sustainable, bioinspired strategy for antibacterial surface engineering using co -deposited coatings of alkali lignin (AL) and cationic polymers (CPs). Derived from renewable AL, the system leverages lignin's natural role as a structural adhesive in plant cell walls, and its photothermal property to enable robust surface modification. AL's polyphenolic structure enables substrate interaction and photothermal activity under near-infrared (NIR) light. High-throughput screening identified CPs that form stable, synergistic complexes with AL. Molecular dynamic simulations reveal that electrostatic interactions govern AL-CP assembly, while van der Waals forces mediate substrate adhesion. The resulting AL-CP coatings exhibit strong mechanical durability, broad substrate compatibility, and long-term chemical stability. Functionally, these coatings deliver potent antibacterial efficacy via a dual mechanism combining “contact-killing” and NIR light-triggered photothermal activation. In a clinically relevant in vivo hernia repair model, AL-CP coatings effectively prevent bacterial infections, demonstrating strong translational potential. This work establishes a green, bioinspired surface modification platform that integrates natural adhesion principles and photothermal functionality, offering a promising solution for infection-resistant interfaces.