ORIGINAL ABSTRACT

The extensive use of glyphosate (Glyp) in agriculture has led to persistent residues in food and the environment, which pose potential threats to ecosystems and human health. Thus, rapid, sensitive, and selective on-site detection strategies are urgently needed. Herein, we developed a smartphone-assisted paper sensor based on a dual-site nanozyme with atomically dispersed Zr-Cu centers anchored on a metal-organic framework (MOF). Compared with the monometallic Cu MOF, the obtained Zr-Cu MOF exhibits an 11.32-fold increase in peroxidase-like activity. In this system, the redox-active Cu site functions as the catalytic center, while the redox-inactive Zr site acts as a Lewis acidic cofactor, modulating the electronic structure of Cu and enhancing substrate binding. Their synergistic interaction facilitates efficient hydrogen peroxide heterolysis and avoids side reactions. Moreover, both Cu and Zr sites contribute to the specific recognition of Glyp, where the phosphonate, carboxyl, and amino groups chelate with Cu through Cu-N/O coordination to form two five-membered rings, while binding to Zr through Zr-O-P coordination. Integrated into a paper-based platform, this Zr-Cu MOF allows fast, naked-eye, and field-deployable Glyp sensing using a smartphone. This work not only provides a general strategy for designing heterometallic nanozymes with multicofactor synergy but also demonstrates a practical platform for pesticide monitoring.