Characterization of magnetic markers for liquid-phase immunoassays using brownian relaxation

Keiji Enpuku; Hideki Watanabe; Yuichi Higuchi; Takashi Yoshida; Hiroyuki Kuma; Naotaka Hamasaki; Masakazu Mitsunaga; Hisao Kanzaki; Akihiko Kandori

doi:10.1143/JJAP.51.023002

Characterization of magnetic markers for liquid-phase immunoassays using brownian relaxation

Keiji Enpuku, Hideki Watanabe, Yuichi Higuchi, Takashi Yoshida, Hiroyuki Kuma, Naotaka Hamasaki, Masakazu Mitsunaga, Hisao Kanzaki, Akihiko Kandori

Research output: Contribution to journal › Article

13 Citations (Scopus)

Abstract

We characterized the magnetic markers used in biological immunoassays based on Brownian relaxation. Because the markers are composed of aggregated nanoparticles, i.e., magnetic nanoclusters, we first clarified their magnetic properties using AC susceptibility measurements, magnetization (M-H) curves, and magnetic relaxation properties. Analyzing the experimental results, we obtained the key parameters for the immunoassay, i.e., hydrodynamic diameter d _h, magnetic moment m _B, and anisotropy energy E _B of the markers. Because these parameters were distributed in practical samples, we took their distribution into account in the analysis. Next, we showed the relationship between these parameters obtained from different samples. It was shown that mB increased approximately in proportion to d _h. On the other hand, no clear correlation between m _B and E _B was obtained. These results were very different from those expected from single-domain nanoparticles and must be taken into account when magnetic markers are used in immunoassays based on Brownian relaxation.

Original language	English
Article number	023002
Journal	Japanese journal of applied physics
Volume	51
Issue number	2 PART 1
DOIs	https://doi.org/10.1143/JJAP.51.023002
Publication status	Published - Feb 1 2012

All Science Journal Classification (ASJC) codes

Engineering(all)
Physics and Astronomy(all)

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Enpuku, K., Watanabe, H., Higuchi, Y., Yoshida, T., Kuma, H., Hamasaki, N., Mitsunaga, M., Kanzaki, H., & Kandori, A. (2012). Characterization of magnetic markers for liquid-phase immunoassays using brownian relaxation. Japanese journal of applied physics, 51(2 PART 1), [023002]. https://doi.org/10.1143/JJAP.51.023002

Characterization of magnetic markers for liquid-phase immunoassays using brownian relaxation. / Enpuku, Keiji; Watanabe, Hideki; Higuchi, Yuichi; Yoshida, Takashi; Kuma, Hiroyuki; Hamasaki, Naotaka; Mitsunaga, Masakazu; Kanzaki, Hisao; Kandori, Akihiko.

In: Japanese journal of applied physics, Vol. 51, No. 2 PART 1, 023002, 01.02.2012.

Research output: Contribution to journal › Article

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abstract = "We characterized the magnetic markers used in biological immunoassays based on Brownian relaxation. Because the markers are composed of aggregated nanoparticles, i.e., magnetic nanoclusters, we first clarified their magnetic properties using AC susceptibility measurements, magnetization (M-H) curves, and magnetic relaxation properties. Analyzing the experimental results, we obtained the key parameters for the immunoassay, i.e., hydrodynamic diameter d h, magnetic moment m B, and anisotropy energy E B of the markers. Because these parameters were distributed in practical samples, we took their distribution into account in the analysis. Next, we showed the relationship between these parameters obtained from different samples. It was shown that mB increased approximately in proportion to d h. On the other hand, no clear correlation between m B and E B was obtained. These results were very different from those expected from single-domain nanoparticles and must be taken into account when magnetic markers are used in immunoassays based on Brownian relaxation.",

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AU - Kuma, Hiroyuki

AU - Hamasaki, Naotaka

AU - Mitsunaga, Masakazu

AU - Kanzaki, Hisao

AU - Kandori, Akihiko

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