TY - GEN
T1 - Immunoassay detection without washing by using AC magnetic susceptibility
AU - Kawabata, Ryuzo
AU - Mizoguchi, Takako
AU - Tsukamoto, Akira
AU - Yoshimura, Tomoko
AU - Kandori, Akihiko
AU - Enpuku, Keiji
PY - 2010/12/1
Y1 - 2010/12/1
N2 - Our aim in this study was to demonstrate a stable immunoassay using the decrease of AC magnetic susceptibility without washing to separate bound and unbound magnetic markers. To achieve low noise in the immunoassay system, we examined the arrangement of the MR sensors, the calibration of the distance between the MR sensor and the sample, and the magnetic noise generated from the motor. The immunoassay system was improved based on these factors, and we detected mouse IgG conjugated polymer beads with anti-mouse IgG antibody-coated magnetic markers. The noise that resulted from the vibration of the MR sensor was decreased to about 1/6 by fixing the MR sensor on the excitation coils. The difference in the magnetic signal from each sample was also decreased from 40 % to 6% by calibrating the distance. Magnetic signal with a high signal-to-noise ratio (SN = 10 or more) was obtained by low-speed rotation (8 rpm) of the sample and the narrow band (5.3 Hz) of the lock-in amplifier demodulating the magnetic signal. The decrease of the AC magnetic susceptibility showed a strong correlation with the concentration of mouse IgG. Sensitivity of the immunoassay system could be estimated as about 4 fmol/ml in terms of molecular concentration. Immunoassay detection using AC magnetic susceptibility enabled a highly sensitive immunoassay without the conventional washing process.
AB - Our aim in this study was to demonstrate a stable immunoassay using the decrease of AC magnetic susceptibility without washing to separate bound and unbound magnetic markers. To achieve low noise in the immunoassay system, we examined the arrangement of the MR sensors, the calibration of the distance between the MR sensor and the sample, and the magnetic noise generated from the motor. The immunoassay system was improved based on these factors, and we detected mouse IgG conjugated polymer beads with anti-mouse IgG antibody-coated magnetic markers. The noise that resulted from the vibration of the MR sensor was decreased to about 1/6 by fixing the MR sensor on the excitation coils. The difference in the magnetic signal from each sample was also decreased from 40 % to 6% by calibrating the distance. Magnetic signal with a high signal-to-noise ratio (SN = 10 or more) was obtained by low-speed rotation (8 rpm) of the sample and the narrow band (5.3 Hz) of the lock-in amplifier demodulating the magnetic signal. The decrease of the AC magnetic susceptibility showed a strong correlation with the concentration of mouse IgG. Sensitivity of the immunoassay system could be estimated as about 4 fmol/ml in terms of molecular concentration. Immunoassay detection using AC magnetic susceptibility enabled a highly sensitive immunoassay without the conventional washing process.
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U2 - 10.1109/ICSENS.2010.5690049
DO - 10.1109/ICSENS.2010.5690049
M3 - Conference contribution
AN - SCOPUS:79951923085
SN - 9781424481682
T3 - Proceedings of IEEE Sensors
SP - 727
EP - 731
BT - IEEE Sensors 2010 Conference, SENSORS 2010
T2 - 9th IEEE Sensors Conference 2010, SENSORS 2010
Y2 - 1 November 2010 through 4 November 2010
ER -