Nanobody-based immunomagnetic separation platform for rapid isolation and detection of Salmonella enteritidis in food samples.

• An epitope-based biopanning strategy was firstly raised. • A nanobody-based immunomagnetic separation platform was proposed for S. enteritidis detection. • The LOD 50 and LOD 95 values of the IMS-ELISA in spiked samples were 6.9 × 103 CFU/25 g or mL and 3.0 × 104 CFU/25 g or mL, respectively. • IMS-ELISA could avoid matrix interference and shorten the enrichment culture time. Rapid separation and identification of Salmonella enteritidis (S. enteritidis) in food is of great importance to prevent outbreaks of foodborne diseases. Herein, by using O and H antigens as targets, an epitope-based bio-panning strategy was applied to isolate specific nanobodies towards S. enteritidis. This method constitutes an efficient way to obtain specific antibody fragments and test pairwise nanobodies. On this basis, a double nanobody-based sandwich enzyme-linked immunosorbent assay (ELISA) coupled with immunomagnetic separation (IMS) was developed to rapid enrich and detect S. enteritidis in food. The detection limit of the IMS-ELISA was 3.2 × 103 CFU/mL. In addition, 1 CFU of S. enteritidis in food samples can be detected after 4-h cultivation, which was shortened by 2 h after IMS. The IMS-ELISA strategy could avoid matrix interference and shorten the enrichment culture time, which has great potential for application in monitoring bacterial contamination in food. [ABSTRACT FROM AUTHOR]