Development of a NiCoFe-LDH/Ketjenblack-enhanced electrochemical antibacterial peptide biosensor for Aeromonas hydrophila detection in seawater samples.

Rapid, sensitive detection of the fish pathogen Aeromonas hydrophila in aquaculture is vital for animal health and preventing economic losses. We provide an electrochemical biosensor for A. hydrophila based on an antibacterial peptide, using a ternary NiCoFe layered double hydroxide (NiCoFe-LDH)- incorporated Ketjenblack as the substrate. This is, to our knowledge, the first A. hydrophila biosensor that is both based on an electrochemical platform using an antibacterial peptide as a biorecognition layer and tested in seawater. The NiCoFe-LDH/Ketjenblack nanocomposite is synthesized via one-pot precipitation. It exhibits a high-activity nanosheet structure with fast electron transfer, as confirmed by XRD, SEM, EIS, and CV. A screen-printed carbon electrode is modified with the interface, coupling LDH-carbon signal amplification with peptide-mediated recognition, with independent support from electrochemical characterization and ligand-tracer affinity studies. Under optimized conditions at room temperature, linearity to 10¹- 10⁶ CFU/mL, LOD of 4.17 CFU/mL and LOQ of 7.34 in 30 min, RSDs < 6%, little cross-reaction with other bacteria, and 97-102% of the PBS response in spiked seawater.