Fast and Sensitive Detection of Salmonella in Milk Samples Using Aptamer-Functionalized Magnetic Silica Solid Phase and MCM-41-Aptamer Gate System.

General detection methods for S. enterica include PCR analysis, immunologic methods, solid culturing techniques, and various microscopic studies. Milk and other food samples demonstrate an especially difficult challenge for direct detection, resulting from high biological contents. In this report, we aimed for fast detection of pathogen cells through an efficient magnetic capture and subsequent quick detection based on aptamer affinity. The Fe3O4@SiO2@pGMA and MCM-41 particles were prepared separately and used for preconcentration and detection, respectively. Aptamer oligonucleotide sequences against S. enterica were fixed on both amine-functionalized MCM-41 and Fe3O4@SiO2@pGMA particles via glutaraldehyde coupling. The captured Salmonella cells were determined by a fluorescent homogeneous assay in the samples by aptamer-gated MCM-41 silica particles. Our method achieved a sensitive assay to detect Salmonella cells in milk samples as low as 103 CFU/ml without any culturing. Hence, the proposed sensing strategy might be an efficient platform for pathogen detection in a food matrix.