Title :
Low Tc SQUID measurement system for magnetic relaxation immunoassays in unshielded environment
Author :
Haller, Andreas ; Matz, Hartmut ; Hartwig, Stefan ; Kerberger, Thomas ; Atzpadin, Heiko ; Trahms, Lutz
Author_Institution :
Phys. Tech. Bundesanstalt, Braunschweig, Germany
fDate :
3/1/2001 12:00:00 AM
Abstract :
A novel technique for detecting immunochemical reactions based on a SQUID measurement system has recently been demonstrated. The reaction partners are labeled by magnetic nanoparticles which, after an immunochemical reaction, display changes of their magnetic relaxation behaviour due to a reduction of their mobility. We have developed a SQUID system dedicated to magnetic relaxation immunoassays (MARIAs) operating in unshielded environment. The system consists of 6 SQUID magnetometers electronically combined to a second-order gradiometer. The gradiometer is formed by electronic subtraction of FLL output signals or by the Three SQUID Gradiometer approach. By evaluating the amplitude of relaxation signals (average of 4 magnetization cycles) a minimum amount of (selected) Fe2O3-particles corresponding to 600 pmol Fe was detected demonstrating the potential of the measurement system for biochemical laboratory diagnostics
Keywords :
SQUID magnetometers; biochemistry; biological techniques; biomagnetism; magnetic particles; magnetic relaxation; FLL electronics; Fe2O3; MARIA; SQUID magnetometer; biochemical diagnostics; immunochemical reaction; low-Tc superconductor; magnetic nanoparticle mobility; magnetic relaxation immunoassay; measurement system; second-order gradiometer; unshielded environment; Current measurement; Frequency locked loops; Immune system; Laboratories; Magnetic analysis; Magnetic separation; Magnetic shielding; Magnetization; Nanoparticles; SQUID magnetometers;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
