Abstract
Immunomagnetic separation has been widely used for the separation and concentration of foodborne pathogens from complex food samples, however it can only handle a small volume of samples. In this paper, we presented a novel fluidic device for the specific and efficient separation and concentration of salmonella typhimurium using self-assembled magnetic nanoparticle chains. The laminated sawtooth-shaped iron foils were first mounted in the 3D-printed matrix and magnetized by a strong magnet to generate dot-array high gradient magnetic fields in the fluidic channel, which was simulated using COMSOL (5.3a, Burlington, MA, USA). Then, magnetic nanoparticles with a diameter of 150 nm, which were modified with the anti-salmonella polyclonal antibodies, were injected into the channel, and the magnetic nanoparticle chains were vertically formed at the dots and verified using a fluorescence inverted microscope. Finally, the bacterial sample was continuous-flow injected, and the target bacteria could be captured by the antibodies on the chains, followed by gold standard culture plating to determine the amount of the target bacteria. Under the optimal conditions, the target bacteria could be separated with a separation efficiency of 80% in 45 min. This fluidic device could be further improved using thinner sawtooth-shaped iron foils and stronger magnets to obtain a better dot-array magnetic field with larger magnetic intensity and denser dot distribution, and has the potential to be integrated with the existing biological assays for rapid and sensitive detection of foodborne bacteria.
Highlights
Since foodborne diseases caused by pathogenic bacteria have posed a great threat to global public health in recent years, it has been essential to explore economical and efficient techniques for the screening of foodborne pathogens [1]
immunomagnetic separation (IMS) has usually been combined with polymerase chain reaction (PCR) [14,15,16], enzyme-linked immunosorbent assay (ELISA) [17,18], and lateral flow chromatography [19,20] to increase their detection sensitivity and shorten their detection time
We propose a fluidic device for immunomagnetic separation of pathogenic bacteria using self-assembled magnetic nanoparticle chains in a fluidic channel
Summary
Since foodborne diseases caused by pathogenic bacteria have posed a great threat to global public health in recent years, it has been essential to explore economical and efficient techniques for the screening of foodborne pathogens [1]. A remarkable study on magnetic flow bioseparation was proposed by Lee et al [23] for rapid separation and detection of pathogenic bacteria in a large volume of food samples using a 3D-printed cylindrical channel. This device was demonstrated to be able to separate and detect the target bacteria in 3 min with a low detection limit of 10 CFU/mL. Salmonella typhimurium with concentrations from 101 to 104 CFU/mL was used to verify the concept and evaluate the performance
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