A novel method to detect Listeria monocytogenes via superparamagnetic lateral flow immunoassay

Anal Bioanal Chem. 2015 Jan;407(2):529-35. doi: 10.1007/s00216-014-8276-8. Epub 2014 Dec 9.

Abstract

A novel strip test system combining immunomagnetic separation with lateral flow immunoassay (LFIA) was established for the accurate detection of Listeria monocytogenes. In this system, a pair of matched monoclonal antibodies was used to construct a sandwich immunoassay, in which superparamagnetic particles were coupled with one of the antibodies as a labeled antibody to capture the target bacteria, while the other antibody was immobilized on the detection zone. After a 20-min reaction, the strips were analyzed by a novel instrument which could detect the magnetic signal of the immunocomplex in a magnetic field. Sensitivity evaluation showed that the limit of detection (LOD) of the superparamagnetic LFIA system for L. monocytogenes was 10(4) CFU/mL, which was at least one log lower than conventional LFIA. No cross-reaction was observed when Salmonella, Escherichia coli O157:H7, or three types of harmless Listeria strains were tested. Further evaluation with actual food samples indicated that the superparamagnetic LFIA system showed 100 % concordance with real-time PCR. Therefore, this novel superparamagnetic LFIA system could be used as a rapid, sensitive, and specific method for the detection of L. monocytogenes.

MeSH terms

  • Antibodies, Immobilized / chemistry
  • Antibodies, Monoclonal
  • Cross Reactions
  • Equipment Design
  • Escherichia coli O157 / immunology
  • Food Contamination / analysis
  • Food Microbiology / methods*
  • Immunoassay / instrumentation
  • Immunoassay / methods*
  • Immunomagnetic Separation / methods
  • Limit of Detection
  • Listeria monocytogenes* / genetics
  • Listeria monocytogenes* / immunology
  • Real-Time Polymerase Chain Reaction
  • Salmonella / immunology
  • Sensitivity and Specificity

Substances

  • Antibodies, Immobilized
  • Antibodies, Monoclonal