Enzyme/Nanozyme Cascade Catalysis-Driven Trimodal Platform Using a Readily Prepared Single-Component Nanozyme for Highly Efficient Metabolic Biomarker Assays.

Nanozyme-based biosensors have aroused much attention in recent decades and were broadly applied to multifarious areas. Whereas, the inferior reliability and high cost/complexity induced by the limited-modal outputs and commonly used multicomponent nanozymes in existing works are still drawbacks that cannot be ignored. Herein, taking galactose (Gal)/xanthine oxidase (XOD) as typical metabolic biomarkers and the facilely obtained ZnTcPP(Fe) MOF as a representative single-component nanozyme, we constructed a universal fluorescent-colorimetric-photothermal trimodal platform that seamlessly integrates high sensitivity, visual readouts, and POCT capability through the rational fusion of target-responsive enzyme/nanozyme tandem catalysis and efficient catalytic oxidation of optical substrates. Collaborative results of spectroscopic experiments, EPR, and DFT calculations manifested the strong electron-transfer ability of Fe-sites within the single-component nanozyme, wherein •OH and O2•- that generated via H2O2 dissociation worked as the pivotal ROS. Noteworthy, the trimodal outputs could achieve multitrack cooperative sensing via their complementary advantages, which evidently improved cost-effectiveness, reliability, and compatibility. The LODs for Gal and XOD were satisfactory in all three modes, which could compete with many previous works. Moreover, this platform demonstrated acceptable adaptability in human serum samples. This work not only provides a canonical paradigm for the accurate analysis of metabolic markers and diagnostics of related diseases but also paves unique pathways for the exploration of economical and robust nanozyme-based multimodal sensors.