Immunomagnetic nanoparticle-based sandwich chemiluminescence-ELISA for the enrichment and quantification of E. coli

Gerhard Pappert, Martin Rieger, Reinhard Niessner, Michael Seidel

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Rapid methods for the quantification of Escherichia coli are required for the monitoring of faecal contamination in water to secure public health. The immunomagnetic separation (IMS) offers rapid enrichment and purification of bacteria in complex matrices and is compatible with immunoassays. By means of this technique, non-target cells and matrix components which might interfere with subsequent analytical methods are removed. We present the synthesis of magnetic nanoparticles (MNPs) and covalent coupling to antibodies against the enterobacterial common antigen (ECA) for use with IMS. Quantification was carried out with a chemiluminescence-based sandwich enzyme-linked immunosorbent assay (ELISA). Our anti-ECA-MNPs allow for a group-specific enrichment of bacterial cells, which can be combined with a species-specific analytical method. The particles were used along with commercially available magnetic columns for the selective enrichment of E. coli from 10-mL water samples. The volumetric enrichment factor was 9. For enriched samples, the limit of detection was reduced from 5.0 × 106 cells·mL-1 to 2.6 × 105 cells·mL-1. Using 200 μL anti-ECA-MNPs, we determined a recovery of 97 ± 6% for a sample containing 106 cells·mL-1 and 89 ± 2% for a sample containing 107 cells·mL-1. The overall time for cell enrichment and detection was 3 h 45 min.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalMikrochimica Acta
Volume168
Issue number1-2
DOIs
StatePublished - Jan 2010

Keywords

  • Chemiluminescence immunoassay
  • Escherichia coli
  • Immunomagnetic separation
  • Magnetic nanoparticles

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