Copper Nanoparticles Loaded on <i>N</i>-Doped Carbon Nanotubes with Enhanced Peroxidase-Like Performance for Gallic Acid Detection in Food

The accurate monitoring of gallic acid (GA) in foodstuffs is crucial for safeguarding human health. The application of nanozymes in colorimetric assays offers a promising route for assessing the GA level. However, the development of high-efficiency and cost-effective nanozymes for quick GA detection holds a substantial challenge. In this study, copper (Cu) nanoparticles (NPs) immobilized on <i>N</i>-doped carbon nanotubes (NCNTs) have been prepared, exhibiting exceptional peroxidase (POD)-like activity for GA detection in food. The anchoring of Cu nanoparticles with NCNTs enables their excellent antioxidant capacity. Then, the obtained Cu NPs/NCNTs show remarkable POD-like activity in catalyzing TMB oxidation, with the attributes of long-term storage stability and reproducibility. Electrochemical assays and radical scavenging experiments reveal a dual mechanism action (involving reactive oxygen species and electron transfer) for the POD-mimicking activity. Furthermore, the developed colorimetric catalytic platform is applied to detect GA in actual tea samples, demonstrating high reliability and potential utility for GA monitoring in the food industry.