Multiplex sorting of foodborne pathogens by on-chip free-flow magnetophoresis

• Published in: Analytica chimica acta 2016-04, Vol.918, p.69-76
• Main Authors: Ngamsom, Bongkot, Esfahani, Mohammad M.N., Phurimsak, Chayakom, Lopez-Martinez, Maria J., Raymond, Jean-Claude, Broyer, Patrick, Patel, Pradip, Pamme, Nicole
• Format: Article
• Language: English
• Subjects: Affinity magnetic separation; Beads; Broths; Chickens; Culture; Enrichment; Escherichia coli; Food enrichment broth; Food Microbiology; Free-flow magnetophoresis; Immunomagnetic Separation - methods; Microscopy, Electron, Scanning; Multiplex sorting; Multiplexing; Populations; Salmonella & E.coli 0157; Salmonella typhimurium; Sorting
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2016.03.014

This study reports multiplex sorting of Salmonella typhimurium and Escherichia coli 0157, from broth cultures and from pathogen-spiked skinned chicken breast enrichment broths by employing microfluidic free-flow magnetophoresis. Magnetic beads of different sizes and magnetite content, namely Dynabeads anti-salmonella and Hyglos-Streptavidin beads together with the corresponding pathogen-specific biotinylated recombinant phages, were utilised as affinity solid phases for the capture and concentration of viable S. typhimurium and E. coli 0157. Following optimisation, the protocol was used to demonstrate continuous magnetophoretic sorting of the two pathogen-bound magnetic bead populations from mixed cultures and from pathogen-spiked chicken pre-enrichment broths under the influence of a Halbach magnet array. For example, in the latter case, a pure population of S. typhimurium-bound Dynabeads (72% recovery) was sorted from a 100 μL mixture containing E. coli 0157-bound Hyglos beads (67% recovery) within 1.2 min in the presence of 0.1% Tween 20. This proof-of-principle study demonstrates how more than one pathogen type can be simultaneously isolated/enriched from a single food pre-enrichment broth (e.g. Universal food enrichment broth). [Display omitted] •We report free-flow magnetophoresis for multiplex sorting of S. typhimurium and E. coli 0157 from spiked food broths.•Pathogens were captured and concentrated using two different types of magnetic beads: Dynabeads and Hyglos.•On-chip magnetophoresis was carried out to separate the pathogen-bound beads in continuous flow.•72% of S. typhimurium-bound Dynabeads and 62% of E. coli0157-bound Hyglos beads were recovered within 1.2 min.