Cascade Amplifying Electrochemical Bioanalysis for Zearalenone Detection in Agricultural Products: Utilizing a Glucose–Fenton–HQ System on Bimetallic–ZIF@CNP Nanocomposites

The integration of advanced materials and signaling cascade strategies is a promising and highly relevant topic for enhancing the performance of bioanalysis. In this study, a three-stage cascade amplification electrochemical bioanalysis (TCAE-bioanalysis) was developed and evaluated for the detection of zearalenone (ZEN). This method couples immunoreaction with a glucose-Fenton-hydroquinone (HQ) system on bimetallic-ZIF (B-ZIF)@CNP nanocomposites. The B-ZIF@CNP-modified gold electrode (AuE) was prepared, offering high conductivity and an excellent reaction interface. The immunoreaction introduced glucose oxidase (GOx) into the glucose-Fenton-HQ system, generating an abundant electron signal. The method achieved an ultrasensitive limit of detection (LOD) as low as 0.87 pg/mL, with an IC₅₀ value of 30.8 pg/mL, representing a 229-fold enhancement in sensitivity compared to ELISA using the same monoclonal antibody (McAb). The specificity, reliability, and practicality of this approach were thoroughly demonstrated for agricultural product samples. Additionally, the TCAE-bioanalysis offers several advantages, including simplified preparation for advanced B-ZIF@CNP, a convenient detection system, and the use of common and environmentally friendly reagents. This study presents a comprehensive approach to improving electrochemical bioanalysis and may also expand the application of signaling cascades and environmentally friendly techniques in other biosensing or diagnostic contexts.