A Portable Biosensing Device With Magnetic Separation And Quantum Dot Bead Labeling For Simple, Rapid, And Quantitative Detection Of Salmonella Typhimurium

Foodborne pathogenic bacteria have caused numerous illnesses and economic losses in the U.S. and the world. It is highly important for food industries to conduct in-field screening for pathogenic bacteria to ensure food safety. The objective of this study was to convert our previously developed optical biosensing method into a portable biosensing device to achieve simple, rapid, and quantitative detection of Salmonella Typhimurium. The device consisted of a control module, a magnetic separation module, and a fluorescence detection module. The bacteria sample, immuno-magnetic nanoparticles, and immuno-quantum dot beads were added into a mixing, separation, and detection chamber and were fully mixed in the control module. The sample was then moved to the magnetic separation module to automatically separate and concentrate the target bacteria. Finally, the fluorescence intensity was measured with the fluorescence detection module to determine the concentration of the target bacteria. The device was able to perform separation and detection of Salmonella with minimal manual operation with a detection limit of 5.4 x 10(2) CFU mL(-1) in 1 h. The device also showed good specificity against four selected non-target bacteria.