Determination of the Magneto-Optical Relaxation of Magnetic Nanoparticles as a Homogeneous Immunoassay
- 7 December 2006
- journal article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 79 (2), 580-586
- https://doi.org/10.1021/ac060491r
Abstract
The interaction between human eotaxin (hEotaxin) and its polyclonal antibody anti-human eotaxin (anti-hEotaxin) was investigated by means of a novel liquid-phase immunoassay using the magneto-optical relaxation of ferrofluids. The binding quality as well as kinetic properties of the binding partners was determined using specifically binding magnetic probes. For this purpose, magnetic nanoparticles (MNP; DDM128N, Meito Sangyo, Japan) were initially functionalized with streptavidin. The biotin-nylated antibody was conjugated with streptavidin-MNP applying the streptavidin−biotin binding system. Binding reactions were detected by measuring the relaxation of the optical birefringence signal occurring when a pulsed magnetic field is applied to the ferrofluid. The addition of hEotaxin to anti-hEotaxin conjugated MNP in different amounts yielded an enlargement of the mean relaxation time due to the formation of MNP aggregates. In order to express the observed increase of the particles' effective diameter in terms of elementary kinetic processes between antigen and antibody, a kinetic model was introduced. Here, the binding reactions are described by a process of stepwise polymerization. The obtained results were compared with data received from surface plasmon resonance biosensor analysis, a standard tool for biomolecular interaction analysis.Keywords
This publication has 10 references indexed in Scilit:
- Biological sensors based on Brownian relaxation of magnetic nanoparticlesApplied Physics Letters, 2004
- Nanoparticle Composition of a Ferrofluid and Its Effects on the Magnetic PropertiesLangmuir, 2004
- A Whole Blood Immunoassay Using Gold NanoshellsAnalytical Chemistry, 2003
- Binding of biological effectors on magnetic nanoparticles measured by a magnetically induced transient birefringence experimentPhysical Review E, 2002
- Dynamic properties of fractions yielded by magnetic fractionation of magnetic fluidsIEEE Transactions on Magnetics, 1999
- Static magneto-optical birefringence of size-sorted nanoparticlesZeitschrift für Physik B Condensed Matter, 1998
- Role of the monocyte chemoattractant protein and eotaxin subfamily of chemokines in allergic inflammationJournal of Leukocyte Biology, 1997
- Human Chemokines: An UpdateAnnual Review of Immunology, 1997
- Experimental design for kinetic analysis of protein-protein interactions with surface plasmon resonance biosensorsJournal of Immunological Methods, 1997
- Magnetic colloidal properties of ionic ferrofluidsJournal of Magnetism and Magnetic Materials, 1986