A bridged diatomic gallium nanozyme with high peroxidase-mimetic activity for melatonin detection.

Abstract

Nanozymes with diatomic sites have emerged as a promising platform to mimic the sophisticated active centers of natural enzymes; however, precisely constructing stable and biomimetic diatomic structures remains a significant challenge. This work presents a biomimetic strategy for constructing a novel bridge-structured gallium diatomic nanozyme (Ga/GY) with Ga-C-C-Ga moieties anchored on graphyne (GY), mimicking the bimetallic active centers of natural metalloenzymes. The unique bridging coordination mode of gallium atoms was unambiguously confirmed through multiple spectroscopic and microscopic characterizations. The as-synthesized Ga/GY exhibits exceptional peroxidase-like activity and enhanced catalytic kinetics, facilitating efficient generation of reactive oxygen species. Leveraging this high enzymatic performance, a sensitive colorimetric sensor was developed for the detection of melatonin, demonstrating excellent stability and detection limits (0.25 μM). This study highlights the significance of diatomic bridging motifs in the rational design of nanozymes and offers new insights into biomimetic catalysis. The developed sensor enabled dynamic, non-invasive monitoring of melatonin metabolism in mouse urine through time-resolved detection based on urine samples collected at different time points after gavage, and this approach provides a simple and intuitive platform for studying the dynamic metabolic behaviors of melatonin and other antioxidants.

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