ED1-4-INV

Properties of Magnetic Nanoparticles in Solutions Evaluated Magnetic Measurement Systems using High-TC SQUIDs

Dec.1 16:15-16:40 (Tokyo Time)

*Toshihiko Kiwa1, Bunta Hiramatsu1, Kei Yamashita1, Wang Jin1, Kenji Sakai1, Keiji Tsukada1

Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University1

Magnetic Nanoparticles (MNPs) have the size of several tens’ nanometers in diameter so that the magnitude of thermal fluctuation of particles are more extensive than their magnitude of magnetic moments. As a result, MNPs generally show superparamagnetic particles, which behave as ferromagnetic particles without coercivity force. Due to this unique magnetic property of MNPs, MNPs are easily dispersed in solutions. Among various kinds of applications of MNPs, medical and biological applications, such as hyperthermia, magnetic nanoparticle imaging, and magnetic immunoassay, could have the potential to realize useful systems for medical/biological diagnosis. MNPs in solution generally change their AC magnetic properties by contained chemicals in the solution so that its essential to evaluate the AC magnetic properties of MNPs in various solutions to realize precise medical/biological diagnosis using MNPs.

 Fig. 1 is the schematic diagram of magnetic immunoassay systems used in our experiments [1]. A sample solution with MNPs was mounted inside an excitation coil, which operates at the frequency of 1 kHz. A gradiometer was coaxially located with the excitation coil. The magnetic signals generated from the MNPs were transferred to an input coil mounted on the high-TC (HTS-) SQUIDs, provided by Superconducting Sensing Technology Research Association (SUSTERA), Japan. Ramp-edge type Josephson junctions were applied in the HTS-SQUID. SmBa2Cu3Oy (SmBCO) and La0.1Er0.95Ba1.95Cu3Oy were used as a base and counter electrode of the junction, respectively. The second and the third harmonic generation (SHG and THG) components of magnetic signals detected by the HTS-SQUID were measured after lock-in amplification.

 In this talk, magnetic measurement systems using HTS-SQUIDs are reviewed, followed by an evaluation of the magnetic properties of MNPs in solutions with various concentrations of sodium ions.

[1] T. Mizoguchi et al., IEEE Trans. Appl. Supercond., 26, 1602004 (2006).

Keywords: HTS-SQUID, Magnetic Nanoparticle, Immnoassay

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