A microfluidic immunosensor for visual detection of foodborne bacteria using immunomagnetic separation, enzymatic catalysis and distance indication
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A disposable visual microfluidic immunosensor is described for the determination of foodborne pathogens using immunomagnetic separation, enzymatic catalysis and distance indication. Specifically, a sensor was designed to detect Salmonella typhimurium as a model pathogen. Magnetic nanoparticles (MNPs) were modified with the anti-Salmonella monoclonal antibodies and then used to enrich S. typhimurium from the sample. This is followed by conjugation to polystyrene microspheres modified with anti-Salmonella polyclonal antibodies and catalase to form the MNP-bacteria-polystyrene-catalase sandwich. The catalase on the complexes catalyzes the decomposition of hydrogen peroxide to produce oxygen after passing a micromixer. The generated oxygen gas increases the pressure in the chip and pushes the indicating red dye solution to travel along the channel towards the unsealed outlet. The travel distance of the red dye can be visually read and related to the amount of S. typhimurium using the calibration scale. The sensor can detect as low as 150 CFU·mL−1 within 2 h.
KeywordsMicrofluidics Distance readout Pathogens detection Enzymatic catalysis Magnetic nanoparticles Polystyrene microspheres Catalase Hydrogen peroxide Chicken samples
This study was supported in part National Natural Science Foundation of China (31802219) and Walmart Foundation (SA17031161). The authors would like to thank Walmart Food Safety Collaboration Center for its great support.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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