ED2-3
Development of dispersion method of magnetic nanoparticles by femtosecond laser pulses for quantitative magnetic immune assay using HTS-SQUID
*Kouhei Kishimoto1, Taiki Yamamoto1, Hiroto Kuroda1, Misaki Tsubota1, Kei Yamashita1, Jin Wang1, Kenji Sakai1, Toshihiko Kiwa1
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan1
Recently, magnetic nanoparticles, are actively used for medical applications. Especially, the magnetic immune assay (MIA) is one of the promising applications because MIA is a more sensitive immune assay than conventional immune assays and does not require washing of unbound antibodies; therefore, MIA realizes faster assay. In our group, we have developed an MIA system with high- TC SQUID [1]. In MIA, magnetic nanoparticles are conjugated with antibodies, and the amount of antigen reacted with the antibodies is measured by measuring AC magnetic susceptivity during the reactions. However, since the magnetic response of magnetic nanoparticles also changes due to the aggregation of the magnetic particles, quantitative measurement of the reaction is difficult to realize [2].
In this study, we proposed to disperse magnetic nanoparticles by a femtosecond pulse laser irradiation. Figure 1 shows the time evolution of the magnetic signal measured by the MIA system. The magnetic particle was 180 nm in diameter, and the iron concertation was approximately 2 mg/ml. The femtosecond laser was irradiated for 60 sec. where the red arrow indicates in Fig 1. The magnitude of the signal gradually decreased because of the aggregation of the particles. The average power, the center wavelength, and the pulse width and reptation rate were 150 mW, 1560 nm, 150 fs, and 70 MHz, respectively. The magnetic signal increased by 8.1% by the femtosecond laser irradiation, which indicates the magnetic nanoparticles disperse. The temperature rise by the laser irradiation is approximately 2.0 ℃, which decreases the magnetic signal by only 5.4%. So, we concluded that the dispersion of the magnetic nanoparticles attributed to the non-thermal effect of the femtosecond laser pulse.
In this presentation, the magnetic measurement system using high-TC SQUID will be described in detail, and the quantitative dispersity will be evaluated at various concentrations and irradiation times.
[1] T. Mizoguchi et al., IEEE Trans. Appl. Supercond, 26, 1602004 (2016).
[2] K. Jinno, et al, AIP Advances, 9(12), 125317 (2019).
Figure 1: Time evolution of magnetic signals from magnetic nanoparticles in the solution. (Arrows indicate the timing of laser irradiation.)
Keywords: Magnetic immune assay, HTS-SQUID, Magnetic nanoparticles
