In-situ growth of PEO/UiO-66(Ce) nanozyme coatings on titanium alloy for antibacterial applications

Abstract

Titanium and titanium alloys face limitations in marine engineering applications due to biofouling. Traditional toxic antifouling coatings contribute to environmental accumulation and biological resistance. Although the nanocatalytic antifouling strategy based on algal enzyme mechanisms shows promise, its effectiveness is limited by resin-based immobilization methods that hinder the exposure of active sites. In this study, we propose an innovative strategy that integrates plasma electrolytic oxidation (PEO) with chemical etching and a solvothermal method to in-situ construct a PEO/UiO-66(Ce) nanozyme coating on the titanium alloy surface. The nanozymes are uniformly anchored on the surface of the TiO₂ porous ceramic layer through hydroxyl interactions and confinement with the hydroxyl-rich nanonetwork, thereby ensuring good structural stability. The sufficient exposure of the active sites facilitates the efficient conversion of H₂O₂ and Br⁻ to HOBr at the catalytic interface. As a result, the PEO/UiO-66(Ce) coating exhibits excellent haloperoxidase-like activity (HPO) and remarkable performance stability. Antibacterial tests show that the PEO/UiO-66(Ce) coating achieves a 97.8 % antibacterial rate against E. coli in the presence of H₂O₂ and Br⁻. Compared to the original TA1, PEO/UiO-66(Ce) significantly reduces the attachment of marine algae, with a coverage rate of only 3.4 % after three days of immersion in Halamphora sp. suspension, which is substantially lower than the 27.6 % observed for TA1. Furthermore, its corrosion current density in a 3.5 % NaCl solution is significantly lower than that of pure TA1. This study provides new insights into the development of high-performance, non-toxic, and environmentally friendly bio-inspired antifouling coatings.