TY - JOUR
T1 - Highly sensitive liquid-phase detection of biological targets with magnetic markers and high Tc SQUID
AU - Uchida, Shinobu
AU - Higuchi, Yuichi
AU - Ueoka, Yuuta
AU - Yoshida, Takashi
AU - Enpuku, Keiji
AU - Adachi, Seiji
AU - Tanabe, Keiichi
AU - Tsukamoto, Akira
AU - Kandori, Akihiko
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/8
Y1 - 2014/8
N2 - We developed a highly sensitive HTS SQUID system for liquid-phase detection of biological targets using magnetic markers. The SQUID consists of a ramp-edge Josephson junction made using an RE123-based multilayer process, and it showed a flux noise of 7.5 μΦ0/Hz1/2 in the white noise region. The 1/f noise was 14 μΦ0/Hz1/2 at f = 1 Hz when the SQUID was operated in AC bias mode. Using the SQUID system, we detected a biological target called biotin. In the experiment, biotins were fixed to a large polymer bead 3.3 μm in diameter. Streptavidin-coated magnetic markers were used for the detection. The bound and unbound (free) markers were magnetically distinguished using the difference in their Brownian relaxation time, i.e., without using a washing process to separate them. The minimum detectable number of biotins was as low as 2×104, corresponding to a sensitivity of 9.5× 10-19 mol/ml. This result indicates that the developed method is highly sensitive. We also show the effect of the excitation field on the signals from free and bound markers for quantitative evaluation of the immunoassay.
AB - We developed a highly sensitive HTS SQUID system for liquid-phase detection of biological targets using magnetic markers. The SQUID consists of a ramp-edge Josephson junction made using an RE123-based multilayer process, and it showed a flux noise of 7.5 μΦ0/Hz1/2 in the white noise region. The 1/f noise was 14 μΦ0/Hz1/2 at f = 1 Hz when the SQUID was operated in AC bias mode. Using the SQUID system, we detected a biological target called biotin. In the experiment, biotins were fixed to a large polymer bead 3.3 μm in diameter. Streptavidin-coated magnetic markers were used for the detection. The bound and unbound (free) markers were magnetically distinguished using the difference in their Brownian relaxation time, i.e., without using a washing process to separate them. The minimum detectable number of biotins was as low as 2×104, corresponding to a sensitivity of 9.5× 10-19 mol/ml. This result indicates that the developed method is highly sensitive. We also show the effect of the excitation field on the signals from free and bound markers for quantitative evaluation of the immunoassay.
UR - http://www.scopus.com/inward/record.url?scp=84898686146&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84898686146&partnerID=8YFLogxK
U2 - 10.1109/TASC.2014.2311449
DO - 10.1109/TASC.2014.2311449
M3 - Article
AN - SCOPUS:84898686146
SN - 1051-8223
VL - 24
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
IS - 4
M1 - 6766191
ER -