A portable toolbox based on time-resolved fluoroimmunoassay and immunomagnetic separation for Cronobacter sakazakii on-site detection in dairy

A portable toolbox based on time-resolved fluoroimmunoassay and immunomagnetic separation was designed for on-site detection of Cronobacter sakazakii in dairy without advanced facilities. In this study, C. sakazakii was recognised and captured in milk by immunomagnetic beads, and europium chelated nanoparticles were used as signal probes in fluoroimmunoassays for quantitative analysis. Under optimal conditions, the capture efficiency of the immunomagnetic beads ranged from 77.76% to 98.26%. The time-resolved fluorescence intensity ratio was used to quantify C. sakazakii (y = 0.2615x - 0.1639, R-2 = 0.9925) in the range of 10(2) to 10(7) cfu mL(-1), and the limit of detection was as low as 73 cfu mL(-1). The assay offered higher sensitivity for a total of 273 actual samples compared with the colloidal gold method. Our method can be completed within 2 h and may be a good model for on-site quantitation of food-borne pathogens with simplicity, rapidity, and cost-effectiveness. (C) 2022 Elsevier Ltd. All rights reserved.