An ultrahighly alkali-adaptive haloperoxidase mimic for phenolic pollutant discrimination and biofilm inhibition in harsh alkaline environments.

Toxic organic pollutants (e.g., phenols) and biofouling represent two major threats to aquatic ecosystems. Nanozymes have emerged as promising agents to mitigate these threats, capable of generating effective antibacterial oxidants as well as monitoring and degrading organic pollutants. However, the practical deployment of many functional nanozymes is severely constrained by their stringent dependence on acidic conditions, rendering them ineffective in prevalent alkaline water systems such as seawater (pH 8.1) and industrial wastewater (pH≥9). Here, we report a facilely synthesized copper phosphonate nanoflower (CPN) as a highly alkali-adaptive haloperoxidase (HPO) mimic to overcome this limitation. CPN maintains efficient and stable catalytic activity across a broad pH range of 7-10 and retains its original efficiency even after 50-day exposure at pH9 and pH10, demonstrating unparalleled alkali tolerance. This exceptional stability originates from a "dynamic surface transformation-activity retention" mechanism, wherein CPN in situ transforms into an equally active copper hydroxide phase, thereby self-adaptively preserving catalytic activity. Leveraging this robust activity, we constructed a multi-channel sensor array capable of discriminating six phenolic compounds over a wide concentration range (40-400 μM) under alkaline conditions. Moreover, the discrimination of the same phenols with different concentrations and phenols mixtures have been achieved. Simultaneously, CPN exhibits excellent bactericidal and anti-biofilm capabilities and can inhibit bacterial adhesion on plastic surfaces under alkaline conditions. This work establishes a versatile nanozyme platform for tackling both chemical and biological hazards in alkaline water environments and proposes a novel strategy for designing alkali-tolerant nanozymes.