A combined experimental and computational study on oxytetracycline electrochemical sensing: Probing the mechanism with a PtNPs/TAPB-TPA-COFs/MWCNTs-OH nanohybrid platform

Monitoring the emission of oxytetracycline (OTC) is crucial for mitigating antibiotic resistance. However, the electrochemical detection of OTC and interfacial electron transfer mechanism remain significant challenges. To address these challenges, this study developed a ternary nanocomposite sensing platform by integrating a covalent organic framework (1,3,5-tris(4-aminophenyl) benzene (TAPB)-terephthalic acid (TPA)-COFs), hydroxylated multi-walled carbon nanotubes (MWCNTs-OH), and platinum nanoparticles (PtNPs). This advanced interface enables highly sensitive and selective electrochemical detection of OTC, while also providing fundamental insights into its interfacial redox behavior. Electrochemical characterizations reveal that the PtNPs/TAPB-TPA-COFs/MWCNTs-OH/glass carbon electrode (GCE) sensor not only exhibits excellent capability in tracking the consecutive oxidation pathways of OTC, but also can sensitively detect OTC at the first oxidation peak with wide liner range from 0.09 to 907.8 μM. By integrating density functional theory computational results with electrochemical experimental evidence, the specific oxidation sites and their transfer mechanisms of OTC are successfully identified for the first time. In the actual sample detection, the sensor shows excellent anti-interference ability and recovery rate (94.4–105.6 %) for OTC in milk matrix, which provides a new technical path for the rapid detection of antibiotic residues in complex matrix.