posted on 2018-01-27, 00:00authored byM. Pacheco, B. Jurado-Sánchez, A. Escarpa
Food
poisoning caused by bacteria is a major cause of disease and
death worldwide. Herein we describe the use of Janus micromotors as
mobile sensors for the detection of toxins released by enterobacteria
as indicators of food contamination. The micromotors are prepared
by a Pickering emulsion approach and rely on the simultaneous encapsulation
of platinum nanoparticles for enhanced bubble-propulsion and receptor-functionalized
quantum dots (QDs) for selective binding with the 3-deoxy-d-manno-oct-2-ulosonic acid target in the endotoxin molecule. Lipopolysaccharides
(LPS) from Salmonella enterica were
used as target endotoxins, which upon interaction with the QDs induce
a rapid quenching of the native fluorescence of the micromotors in
a concentration-dependent manner. The micromotor assay can readily
detect concentrations as low as 0.07 ng mL–1 of
endotoxin, which is far below the level considered toxic to humans
(275 μg mL–1). Micromotors have been successfully
applied for the detection of Salmonella toxin in food samples in 15 min compared with several hours required
by the existing Gold Standard method. Such ultrafast
and reliable approach holds considerable promise for food contamination
screening while awaiting the results of bacterial cultures in a myriad
of food safety and security defense applications.