Cu-CDs/ABEI@Ag with peroxidase-like catalytic activity for chemiluminescence sensing of glyphosate residues in coffee

In this study, an “off” signal chemiluminescence (CL) sensor was designed for the detection of glyphosate (Gly) based on Cu-CDs/ABEI@Ag as CL enhancers. Copper-doped carbon dots (Cu-CDs) was synthesized through a sample microwave digestion approach, and AgNO 3 was reduced to silver nanoparticles (AgNPs) utilizing N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and prepared Cu-CDs as mild reducing agents. The Cu-CDs and AgNPs demonstrated peroxidase (POD)-like properties, facilitating the breakdown of H 2 O 2 into reactive oxygen species (ROS) such as ∙OH, ∙O 2 − , and 1 O 2 to generate CL signal. By integrating ABEI into the catalyst system, the CL reagent became concentrated within the catalyst structure, minimizing the spatial separation between the catalyst and ABEI, thus amplifying the CL response. Notably, Gly can inhibit POD-like activity by interaction between Cu-CDs/ABEI@Ag and Gly, thus decrease the CL intensities produced from oxidation of ABEI. Based on this highly sensitive “off” response in CL, a CL nano-sensor was developed for Gly detection, achieving a detection limit of 3.87 μg/L. Furthermore, satisfactory spiked recovery rates (95.86–111.13%) were obtained in coffee samples, highlighting the sensor's promising applicability for on-site Gly monitoring.