Fluorescent and colorimetric detection of Vibrio anguillarum based on loop-mediated isothermal amplification coupled...

Vibrio anguillarum poses a serious threat to food safety, human health and aquaculture. At present, sensitive visual detection methods for V. anguillarum remain scarce. In this study, a novel dual-signal sensing system was constructed for the highly specific and visual detection of V. anguillarum. The system leverages loop-mediated isothermal amplification (LAMP) reaction to generate abundant AT-rich double-strand DNA products in the presence of the target pathogen. These products serve as templates for in-situ synthesis of copper nanoclusters (CuNCs), which exhibit both strong fluorescence and peroxidase-mimicking activity. The fluorescence intensity of CuNCs was positively correlated with the concentration of V. anguillarum, enabling quantitative fluorescence detection. Simultaneously, the CuNCs with peroxidase-like activity can catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB, allowing straightforward colorimetric readout. This dual-mode approach achieved outstanding sensitivity, with detection limits as low as 18 CFU/mL for fluorescence and 108 CFU/mL for colorimetry. The system also demonstrated high specificity against related pathogenic bacteria and was successfully applied to detect V. anguillarum in real turbot samples, showing excellent recovery and reliability. Notably, a closed-vial configuration effectively minimized aerosol-derived carryover contamination, and a portable colorimetric test paper further enabled visual point-of-care analysis. This work provides a robust and versatile strategy for rapid, visual, and accurate detection of V. anguillarum, and serves as a reference for developing detection platforms for other pathogens.