Stimuli-responsive composite coating based on dynamic metal-ligand interactions for sustainable marine antifouling

While copper-based antifoulants represent effective solutions for marine biofouling prevention, their utilization efficiency remains a critical challenge. This investigation demonstrates a pH-responsive hydrogel composite through synergistic integration of poly(acrylic acid) networks with histidine-coordinated cupric nanoclusters. The main ligand configuration of histidine and Cu 2+ was identified as “imidazole-dominated and carboxyl-assisted” by density functional theory (DFT) simulation, which provides theoretical support for the pH sensitivity of hydrogel. This coating releases Cu 2+ precisely “on demand” in response to external pH changes, effectively preventing algae and fouling organisms from adhering and achieving high bactericidal rates against Pseudomonas aeruginosa and E. coli . The distinctive molecular design of the coating combines multiple amide motifs that self-assemble into a honeycomb network via strong hydrogen bonding, while the coordination between Cu 2+ and histidine establishes a dynamic metal-ligand interaction with tunable dissociation kinetics and cohesion strength. This intelligent controlled-release composite hydrogel significantly reduces the risk of marine fouling by releasing antifouling agents precisely and efficiently, providing an innovative solution for building a sustainable marine antifouling system.