Interfacial engineering-tailored Mn-clay-based nanozyme for glyphosate laccase-amplified sensing and inhibitor...

Monitoring pesticide residues and lanthanide metals in water system is crucial for safeguarding human health and environmental integrity. Herein, we precisely designed a type of Mn-clay-based composite nanozyme via interfacial engineering and, for the first time, evaluated the effect of the interfacial configuration of glyphosate (Glyp) on laccase-like activity using in-situ ATR-FTIR spectroscopy and mass spectrometry. DFT calculations revealed that the phosphonate group interacts with Mn - Mn to form inner-sphere complexes with multiple configurations tailoring electron transfer and redox ability. Ce³⁺, serving as a hitherto unreported inhibitor of Glyp, can induce the self-coupling consumption of free Glyp, and irreversibly "turn off" latter interfacial laccase-amplification effect by changing its reactive adsorbed configuration. A similar phenomenon can be witnessed in other lanthanide metals (Ln³⁺), e.g., La³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺ and Er³⁺. With this in mind, an "on-off" enzyme-free nanosensor was designed based on laccase-mimicking cascade catalytic reaction for the selective recognition of Glyp and Ln³⁺. Our nanosensor demonstrates a good linear relationship with Glyp in a wide range of 0-0.2 mM (0-3 μM for Ce³⁺), with a low LOD of 61 nM for Glyp and 94 nM for Ce³⁺. Additionally, it exhibits high selectivity and anti-interference ability under the co-application of inorganic fertilizers and multiple pesticides. This study presents a novel molecular-level structure-activity relationship between Glyp/Ln³⁺ and laccase-related efficiency, and provides prerequisites for the risk assessment of contaminants such as Glyp and Ln³⁺ in a single system.