Environmental light-activated nanozymes for efficient inactivation of harmful algae and associated hemolytic toxin.

[Display omitted] • VCN shows visible light-activated oxidase-like activity. • VCN eliminates harmful algae and algal toxin within 4 h. • VCN removes harmful algae by inducing oxidative stress inside algal cells. Harmful algal blooms (HABs) pose a significant threat to aquatic ecosystems. Conventional anti-algal methods are associated with low anti-algal efficiency, and absence of treatment of toxins released by algae. Therefore, it is essential to establish effective HAB prevention strategies. Artificial nanozymes have a great potential in combating HABs due to their unique catalytic properties. An ultra-small carbon dots nanozyme (VCN) with oxidase-like activity was synthesized in this study. VCN exerts its catalytic effect by catalyzing the production of reactive oxygen species (ROS) from oxygen. VCN was utilized to inactivate hazardous marine algae based on its catalytic properties. It was found that VCN could rapidly remove more than 90% of harmful algae (Skeletonema costatum and Phaeocystis globosa) in just 4 h under environmental visible light. To the best of our knowledge, the algae removal efficacy is greater than that of previous reports. Additionally, VCN could attenuate the toxicity of toxins released by algae to counteract secondary pollution caused by algal fragmentation, which is important for practical applications in water pollution caused by algae. Collectively, under applicable and mild conditions, the VCN-presented enzyme activity can efficiently reduce HABs caused harmful pollution. [ABSTRACT FROM AUTHOR]