Visualization and quantitative detection of Shigella sonnei by phage-directed nanozyme

Shigella sonnei, a prevalent foodborne zoonotic pathogen, exhibits a high transmission rate in regions with poor healthcare infrastructure and limited resources. This pathogen is commonly associated with dairy, animal, fruit, and vegetable products, causing considerable safety concerns in clinical and food processing. In this study, the lytic phage vB_SsP_LW was immobilized onto the surface of a magnetic Fe3O4 nanozyme via amidation, resulting in the formation of the composite vB_SsP_LW@Fe3O4, which exhibits a peroxidase-like activity. This composite can oxidize TMB to TMBox in the presence of H2O2 and TMB within 15 min, facilitating the detection of S. sonnei at a detection limit of 12 CFU/mL. The recovery rate of the detection method ranges from 91.87% to 106%, with a relative standard deviation between 1.4% and 5.6%. Furthermore, this method exhibits specificity, making it challenging to identify other bacterial species. These findings indicate the application potential of vB_SsP_LW@Fe3O4 in food safety detection.