High-Coordination Single-Atom Nanozyme-Based Colorimetric-Photothermal Sensing Platform for Evaluation of Total Antioxidant Capacity

The dual-mode sensing platform effectively integrates the contributions of individual channels, thereby improving the accuracy and reliability of analytical results in complex samples. In this study, a high-coordination nanozyme featuring an atomically dispersed Fe–N 6 structure (Fe-NC) was reported, integrating colorimetric detection with dual enzyme-like activities and photothermal sensing for three-channel evaluation of total antioxidant capacity (TAC). The Fe-NC single-atom nanozyme with an Fe–N 6 structure exhibited high stability after O 2 /H 2 O 2 adsorption and enhanced oxidase-like and peroxidase-like activities. The dual enzyme-like activities facilitated the oxidation of 3,3′,5,5′-tetramethylbenzidine, thereby amplifying both colorimetric and photothermal responses. This enabled the development of a three-channel dual-mode sensing platform for AA quantification and TAC evaluation. The two independent modes exhibited wide detection ranges and low detection limits and produced highly consistent responses for TAC in real samples. This indicates that detection channels can be flexibly selected according to the analyte concentration. All three channels can be used for self-validation, thereby reducing systematic errors associated with single-mode detection. Therefore, the three-channel dual-mode sensing platform demonstrates favorable reliability and heightened analytical accuracy, highlighting its broad application potential in food analysis.