Rapid On-Site Low-Cost Detection of Aeromonas hydrophila in Fish via Direct Sample Loading on a Molecularly Imprinted Polymer Electrode

Aeromonas hydrophila ( A. hydrophila ) is a ubiquitous aquatic pathogen responsible for devastating outbreaks in aquaculture and an emerging food- and waterborne threat to human health. Rapid and reliable on-site diagnostics are crucial for disease surveillance and food safety. Herein, we report the development of a novel molecularly imprinted polymer (MIP)-based electrochemical biosensor utilizing a screen-printed electrode (SPE) for the rapid (< 5 min) detection of A. hydrophila directly in fish tissue homogenates. The integration of methylene blue during the electropolymerization process resulted in highly conductive and stable binding cavities, achieving a low limit of detection (LOD) of 10 1 CFU/mL with a broad linear range up to 10 6 CFU/mL. The sensor demonstrated excellent selectivity, exhibiting negligible cross-reactivity with Escherichia coli , Staphylococcus aureus , and Listeria monocytogenes . Furthermore, the platform successfully distinguished infected from healthy Cyprinus carpio samples in clinical field trials. Compared to conventional qPCR and ELISA techniques, this portable, cost-effective, and user-friendly biosensor presents a highly practical alternative for real-time aquaculture biosecurity monitoring and post-harvest food safety assurance.