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Use of External Magnetic Fields to Reduce Reaction Times in an Immunoassay Using Micrometer-Sized Paramagnetic Particles as Labels (Magnetoimmunoassay)

Luxton, Richard; Badesha, Jasvant; Kiely, Janice; Hawkins, Peter


Richard Luxton
Research Centre Director-IBST/Professor

Jasvant Badesha

Janice Kiely
Professor in Bio-electronics/Res In CoDi

Peter Hawkins


The paper presents a rapid immunoassay system capable of quantifying analyte in complex biological and environmental media. Antibody-coated micrometer-sized paramagnetic particles are used as labels in an assay in which they bind quantitatively with an analyte and capture antibody molecules immobilized on a polyester disk to form a sandwich assay. The assay is performed in a simple reaction vessel, and reactions between labels, analyte, and antibodies are accelerated by positioning magnets alternately above and below the vessel. The bound paramagnetic particles are quantified using a simple flat, spiral, coil located just below the polyester disk. The electronic circuitry associated with the coil uses components that are inexpensive and readily available. The coil has been designed to respond only to particles bound on the disk and not to unbound particles still in the test solution. Unbound particles are pulled away from the disk by the magnet before readings are taken. The use of the reaction vessel with the cardiac markers CRP and CKMB is described. No sample preparation or washing step is used in the assays, and results can be obtained in less than 3 min after introducing the sample into the vessel with sensitivities in the normal clinical range.


Luxton, R., Badesha, J., Kiely, J., & Hawkins, P. (2004). Use of External Magnetic Fields to Reduce Reaction Times in an Immunoassay Using Micrometer-Sized Paramagnetic Particles as Labels (Magnetoimmunoassay). Analytical Chemistry, 76(6), 1715-1719.

Journal Article Type Article
Publication Date Mar 15, 2004
Journal Analytical Chemistry
Print ISSN 0003-2700
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 76
Issue 6
Pages 1715-1719
Keywords external magnetic fields, reaction times, immunoassay, micrometer-sized paramagnetic particles, labels, magnetoimmunoassay
Public URL
Publisher URL http:\\\10.1021/ac034906+
Additional Information Additional Information : This paper describes a rapid immunoassay system which provides a result in minutes; traditional immunoassays having assay times in excess of an hour. An invitation to give a plenary lecture at the prestigious Oak Ridge Conference organised by the American Association for Clinical Chemistry illustrates the work is internationally recognised. This work has instigated eight further collaborative projects with companies/bodies such as DSTL, Fort Halstead [Alistair Hutchinson], Birmingham University [Mark Colclough] and Gaiker TC, Bilboa [Javier Escobal]. The work is the basis of three international patents (two granted in a number of countries and one pending).