Dual-signal cross-validation via ECL quenching and DPV oxidation on a MIP sensor: ultrasensitive detection of sulfadiazine in complex food matrices with a CD-COF core

The excessive use of sulfadiazine (SDZ) poses significant health risks due to toxic residues in food and ecosystems. This work introduces a novel molecularly imprinted polymer (MIP) sensor featuring a carbon dot-based covalent organic framework (CD-COF) core as a high-performance electrochemiluminescence (ECL) emitter. Upon SDZ rebinding to imprinted sites, the sensor leverages SDZ's inherent redox activity to enable complementary differential pulse voltammetry (DPV) detection alongside ECL quenching. This dual-signal output establishes an intrinsic cross-validation mechanism that inherently corrects environmental interferences. The sensor achieves ultrasensitive detection of SDZ, with impressively low detection limits of 0.28 nM (ECL) and 1.6 nM (DPV). Validation in food matrices demonstrates exceptional accuracy and reliability, yielding recoveries of 91–110%. This study not only provides a robust tool for trace SDZ monitoring but also establishes a new paradigm for CD-COF-powered MIP sensors integrating dual-mode signals for highly reliable contaminant analysis in real-world samples.