Polymer donor PM6 assisted solid-state electrochemiluminescence sensor of copper-doped biomass carbon quantum dots for ultrasensitive detection of rhodamine B in chili powder

In this study, we developed novel copper-doped biomass carbon quantum dots (Cu-CQDs) utilizing cantaloupe peel and copper nitrate as precursors. Compared to undoped biomass carbon quantum dots (CQDs), the Cu-CQDs demonstrated a stronger electrochemiluminescent (ECL) signal when reacting with K 2 S 2 O 8 . By employing the synthesized Cu-CQDs as a luminescent reagent, we collaborated with the polymer donor PM6 to construct an innovative solid-state ECL sensor for the trace detection of Rhodamine B (RhB). The solid-state ECL sensor was developed using a layer-by-layer modification approach, sequentially modifying the electrode surface with the polymer donor PM6, Cu-CQDs, and chitosan (CS). The layered structure of the polymer donor PM6 serves as a carrier for Cu-CQDs, enhancing their effective concentration on the electrode surface. Additionally, its electron-donating properties facilitate electron transfer within the sensor system. Chitosan (CS), characterized by its viscosity, was modified as the outermost layer, further enhancing the stability and ECL intensity of the sensor. RhB exhibited a significant quenching effect on the ECL signal of the constructed sensor, with the quenching value being proportional to the logarithm of RhB concentration in the range of 5.0 × 10 −8 to 5.0 × 10 −13  M. This sensor was successfully applied to the detection of RhB in chili samples, providing an effective platform for food safety monitoring.