Detection of 8 nm Diameter Superparamagnetic Beads by Magnetically-Induced Manipulation of Micrometer-Sized Magnetic Beads: A Novel Protocol for Magnetically-Labeled Biosensing

Biosensing platforms based on functionalized superparamagnetic beads acting as "magnetic-labels" show tremendous potential for rapid and highly-sensitive point of care medical diagnosis. Recently, for greater quantification, there are increasing demands for the use of magnetic labels with...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2010-04, Vol.49 (4), p.04DL07-04DL07-3
Main Authors: Morimoto, Yoshitaka, Takamura, Tsukasa, Park, Sang Yoon, Sakamoto, Satoshi, Kawata, Shintaro, Handa, Hiroshi, Sandhu, Adarsh
Format: Article
Language:English
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Summary:Biosensing platforms based on functionalized superparamagnetic beads acting as "magnetic-labels" show tremendous potential for rapid and highly-sensitive point of care medical diagnosis. Recently, for greater quantification, there are increasing demands for the use of magnetic labels with diameters of 8--150 nm, which are comparable in size to actual biomolecules. However, detection of small numbers of sub-150 nm sized magnetic beads by magnetoresistive device-based platforms is extremely challenging due to the intrinsic noise of these electronic devices. Here, we describe an easy and economical detection method of low areal densities of 8-nm-diameter superparamagnetic "target beads" immobilized over millimeter-sized substrates by optically monitoring the magnetically induced "capture" of easily visible, micrometer sized superparamagnetic "columnar beads" by the targets in less than a few tens of seconds.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.49.04DL07