A Rapid and Specific Biosensor for Salmonella Typhimurium Detection in Milk

This paper reports the application of an amperometric biosensor for rapid and specific Salmonella Typhimurium detection in milk. This device was developed from self-assembled monolayer technique on a gold screen-printed electrode, using cysteamine thiol. Polyclonal antibodies were oriented by protein A immobilization. The biosensor structure was characterized by cyclic voltammetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. The analytical response was obtained by a chronoamperometry technique, using a direct-sandwich peroxidase-labeled system. The biosensor device showed a qualitative behavior with a very low limit of detection of 10 CFU mL−1 and a detection time of 125 min. The biosensor specificity was demonstrated in pure and mixed samples with strains of Escherichia coli and Citrobacter freundii. The performance of the biosensor was found satisfactory, and the device was tested in skimmed and whole milk samples, being able to detect S. Typhimurium quickly, without an enrichment step. This structure of immunosensor assembly can be expended in future studies for other food matrices and bacterial species, making it a useful tool to ensure food safety.