Dual-metal-site MOF nanozyme with enhanced activity for highly sensitive colorimetric detection of Cr(VI) in dairy
Mengyue Gao1, Zhiheng Li2, Mengjie Liu3
1Institute of Environment and Safety, Wuhan Academy of Agricultural Sciences, Wuhan 430072, China.
Abstract:
A dual-metal-site metal-organic framework (DMS MOF) nanozyme was developed for highly sensitive colorimetric detection of Cr(VI) in dairy products. DMS MOF nanozyme integrates trivalent iron nodes and iron-porphyrin ligands to mimic the multi-center natural oxidoreductases, with adjacent dual-metal centers synergistically enhancing catalytic activity. Steady-state kinetic analyses and Zeta potential investigations demonstrate that the DMS MOF exhibits significantly lower Michaelis-Menten constants and enhanced substrate affinity than single-metal-site MOFs. The proposed method based on DMS MOF nanozyme enables highly sensitive colorimetric sensing of Cr(VI) within merely 5 min, achieving a broad linear range from 0.50 ppb to 5.0 ppm and a limit of detection (LOD) of 0.36 ppb. Furthermore, the developed strategy has been validated in complex dairy products including pure milk, yogurt, and milk powder, yielding recoveries of 84.0-110% with RSD ≤2.10%. Thus, engineered DMS-MOF nanozymes with enhanced activity provide a cost-effective, reliable approach for heavy-metal detection in foods.
