Size distribution of magnetic marker estimated from ac susceptibility in solution for biosensor application

Keiji Enpuku, Tsuyoshi Tanaka, Yuya Tamai, Feng Dang, Naoya Enomoto, Junichi Hojo, Hisao Kanzaki, Naoki Usuki

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

The ac susceptibility of magnetic markers in solution was studied for biosensor application, where the marker consisted of magnetic nanoparticles and a coating material. From the frequency dependence of the susceptibility caused by the Brownian rotation of the marker, we estimated the distribution of marker size, which is an important parameter for biosensor application. For this purpose, we analyzed the experimental data by the singular value decomposition (SVD) method. Using this method, we can directly estimate the size distribution without assuming any distribution function. The estimated distributions were also compared with those obtained from optical dynamic light scattering (DLS) measurements. It was shown that the size distribution estimated by magnetic measurement (SVD) slightly shifts to a size lower than that estimated by the optical measurement (DLS). It was also shown that the frequency dependence of the susceptibility can be better explained by the size distribution estimated by the SVD method than by the distribution estimated with DLS. The difference between the magnetic and optical measurement results was discussed in terms of aggregation of the markers.

Original languageEnglish
Pages (from-to)7859-7865
Number of pages7
JournalJapanese journal of applied physics
Volume47
Issue number10 PART 1
DOIs
Publication statusPublished - Oct 1 2008

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

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