Title :
A Compact SQUID Magnetometer for Thermoremanent Magnetization Immunoassays
Author :
Carvalho, H.R. ; Bruno, A.C.
Author_Institution :
Dept. of Phys., Pontificia Univ. Catolica do Rio de Janeiro, Rio de Janeiro, Brazil
fDate :
6/1/2011 12:00:00 AM
Abstract :
We built a detection system for biosensors used in immunoassays containing superparamagnetic nanoparticles, based on a bulk rf-SQUID and a coreless electromagnet. In this system, a thermoremanent magnetization technique is used by lowering the temperature of the sample below their blocking temperature while applying a small magnetic field. Once inside liquid helium they are displaced through one the SQUID holes. Commercial dextran and polymer coated nanoparticles with 50 nm and 176 nm external diameters containing iron oxide core were used in the experiments. Our SQUID system was able to detect magnetic moments down to 24 × 10-15 Am2.
Keywords :
SQUID magnetometers; biomagnetism; biomedical measurement; biosensors; electromagnets; magnetic moments; magnetic particles; nanobiotechnology; nanoparticles; remanence; superparamagnetism; biosensors; blocking temperature; bulk RF-SQUID; compact SQUID magnetometer; coreless electromagnet; detection system; dextran; iron oxide core; liquid helium; magnetic moments; polymer coated nanoparticles; size 176 nm; size 50 nm; superparamagnetic nanoparticles; thermoremanent magnetization immunoassays; Inductance; Magnetic cores; Magnetization; Magnetometers; Nanoparticles; SQUIDs; Superconducting magnets; Immunoassays; SQUIDs; magnetic nanoparticles; superparamagnetism;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2010.2081332
