Self-limited catalysis in phosphatase-mimicking nanozymes for redox-interference-resistant polyphosphate assay

Nanozyme-based sensing platforms have been widely exploited for food safety detection; however, their practical application is severely hindered by inherent redox interference within complex matrices. Herein, we leveraged the self-limited catalysis of phosphatase-mimetic nanozymes to engineer a colorimetric polyphosphate sensor, which fundamentally eliminates undesired non-specific redox interference. A zirconium-based metal-organic framework nanozyme, Zr-MOF-TDC, was rationally synthesized via ligand engineering. This nanozyme selectively catalyzes the hydrolysis of phosphomonoester bonds under neutral pH condition, while displaying no detectable activity toward carboxyl ester, and phosphodiester. Critically, the phosphatase-mimicking activity functions independently of redox site, endowing the nanozyme with negligible oxidase- or peroxidase-like activity. Besides, the phosphate products formed in situ competitively occupy the Lewis acid sites through stable Zr-O-P interactions, triggering the self-limited inhibition of its catalytic activity. On this basis, we constructed a colorimetric platform for quantitative detection of polyphosphate food additives. The sensor shows a linear response to sodium tripolyphosphate in the range of 1.0–10.0 μmmol/L, and delivers outstanding anti-interference capability against 1.0 mmol/L reducing substances (ascorbic acid and glutathione). This work not only provided a reliable tool for rapid screening of phosphate additives, but also established a self-limited strategy for designing anti-interference nanozyme sensing systems.