Potential-Resolved Electrochemiluminescence via Interfacial Electronic Engineering in Au25@FeMOP Heterostructures for Intelligent Urine Analysis.

Precise modulation of reactive oxygen species (ROS) pathways is pivotal for advanced electrochemiluminescence (ECL) sensing. However, achieving this in complex biofluids remains a formidable challenge. Herein, we report a hierarchical hollow nanocomposite (Au25@FeMOP) by confining atomically precise Au25(Cys)18 nanoclusters within an Fe-porphyrin-based microporous organic polymer. Spectroscopic analysis and density functional theory (DFT) calculations reveal a robust Au-Cys-Fe interfacial bridge. This linkage facilitates directional electron transfer from Au clusters to Fe single-sites. Such electronic coupling optimizes the d-band center and spin density of the Fe centers, thereby refining the adsorption of oxygen intermediates. Consequently, the Au25@FeMOP architecture exhibits unique potential-resolved ECL behavior. It selectively catalyzes superoxide radical (O2•-) generation at cathodic potentials and switches to hydroxyl radical (•OH) production at anodic potentials. Leveraging this switchable mechanism, we constructed an intelligent sensing platform. This system generates distinct ECL "fingerprints" for various urinary metabolites, enabling the precise discrimination of key components in simulated urine. This work elucidates the atomic-level synergistic mechanism of bimetallic ECL catalysts and establishes a new pathway for noninvasive health monitoring.