Two birds with one stone: Interfacial controls and pH response for long-term and high-efficiency Cu2O antibacterial materials

Cu2O is the current mainstream antifouling agent, but it has problems such as explosive release of Cu2+ ions, poor sterilization effect, and environmental pollution. In this work, we used the weakly acidic solution generated during the preparation of Cu2O@Ag to dissolve chitosan (CS) and then prepared Cu2O@Ag@CS core-shell nanocomposites using a one-pot method. The emergence of Cu2O@Ag@CS composites solved the above mentioned problems of Cu2O. The CS shell can protect the Cu2O well, avoid direct contact with the outside environment, and reduce the oxidation of Cu2O. In addition, the CS shell provided a pH-response performance, and made Cu2O crystal face more active. The acidic environment generated by bacteria and other microorganisms opened the CS shell, causing Cu2O@Ag@CS to release a large amount of Cu2+ ions. In a neutral or alkaline environment, the release of Cu2+ ions were less, greatly improving the utilization efficiency of Cu2+ ions. Ag nanoparticles deposited onto the surface of Cu2O further protected Cu2O from oxidation, significantly improving the photocatalytic efficiency of Cu2O and enhancing its sterilization efficiency. The antibacterial properties of CS itself with more holes also benefited the improvement in the sterilization effect of Cu2O@Ag@CS. A 30-day long-acting antibacterial experiment proved the long-acting and high-efficiency antibacterial properties of Cu2O@Ag@CS composites. After the antifouling coating with Cu2O@Ag@CS as an antifouling agent was hung in a marine environment for 70 days in summer, no microorganisms attached onto the surface, proving the excellent practical application performance of Cu2O@Ag@CS antifouling agent.