Magnetophoretic immunoassay of allergen-specific IgE in an enhanced magnetic field gradient

Young Ki Hahn, Zongwen Jin, Joo H. Kang, Eunkeu Oh, Min Kyu Han, Hak Sung Kim, Jung Tak Jang, Jae Hyun Lee, Jinwoo Cheon, Seung Hyun Kim, Hae Sim Park, Je Kyun Park

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77 Citations (Scopus)


We demonstrate a novel magnetophoretic immunoassay of allergen-specific immunoglobulin E (IgE) based on the magnetophoretic deflection velocity of a microbead that is proportional to the associated magnetic nanoparticles under enhanced magnetic field gradient in a microchannel. In this detection scheme, two types of house dust mites, Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus), were used as the model allergens. Polystyrene microbeads were conjugated with each of the mite extracts followed by incubation with serum samples. The resulting mixture was then reacted with magnetic nanoparticle-conjugated anti-human IgE for detection of allergen-specific IgE by using sandwich immuno-reactions. A ferromagnetic microstructure combined with a permanent magnet was employed to increase the magnetic field gradient (∼104 T/m) in a microfluidic device. The magnetophoretic velocities of microbeads were measured in a microchannel under applied magnetic field, and the averaged velocity was well correlated with the concentration of allergen-specific IgE in serum. From the analysis of pooled sera obtained from 44 patients, the detection limits of the allergen-specific human IgEs for D. farinae and D. pteronyssinus were determined to be 565 (0.045 IU/mL) and 268 fM (0.021 IU/mL), respectively. These values are 1 order of magnitude lower than those by a conventional CAP system. For evaluation of reproducibility and accuracy, unknown sera were subjected to a blind test by using the developed assay system, and they were compared with the CAP system. As a result, coefficient of variance was less than 10%, and the developed method enabled a fast assay with a tiny amount of serum (∼10 μL).

Original languageEnglish
Pages (from-to)2214-2220
Number of pages7
JournalAnalytical Chemistry
Issue number6
Publication statusPublished - 2007 Mar 15

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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