Spiky MnO₂ microparticles as an interface-driven mechanochemical antibacterial platform

Bacterial infections, particularly those associated with biofilms, remain difficult to treat because bacteria are protected by the extracellular polymeric matrix and the local microenvironment. In this work, we developed spiky manganese dioxide (SP-MnO₂) microparticles serving as an interface-driven mechanochemical antibacterial platform combining topology-associated interactions with nanozyme activity. The spiky morphology facilitated bacterial capture and promoted close contact between bacteria and material, providing a structural basis for mechano-bactericidal interactions. At the same time, MnO₂ consumed glutathione and promoted reactive oxygen species generation through its nanozyme activity, thereby weakening antioxidant buffering and inducing oxidative damage near bacterial surfaces. Through this combined mechanochemical action, SP-MnO₂ achieved >97% antibacterial efficiency against planktonic bacteria, inhibited biofilm formation, and partially disrupted mature biofilms in vitro. Mechanistic comparisons further showed that the spiky morphology made a substantial contribution to the antibacterial activity by promoting bacteria-material interactions and localized oxidative damage. SP-MnO₂ also exhibited acceptable short-term cytocompatibility and hemocompatibility. Overall, this work introduces a proof-of-concept antibacterial platform and provides a rational strategy for enhancing antibacterial activity through morphology-regulated bacteria-material interfaces.