Frequency-domain birefringence measurement of biological binding to magnetic nanoparticles.
Optical detection of the frequency-dependent magnetic relaxation signal is used to monitor the binding of biological molecules to magnetic nanoparticles in a ferrofluid. Biological binding reactions cause changes in the magnetic relaxation signal due to an increase in the average hydrodynamic diameter of the nanoparticles. To allow the relaxation signal to be detected in dilute ferrofluids, measurements are made using a balanced photodetector, resulting in a 25 μV/√Hz noise floor, within 50% of the theoretical limit imposed by photon shot noise. Measurements of a ferrofluid composed of magnetite nanoparticles coated with anti-IgG antibodies show that the average hydrodynamic diameter increases from 115.2 to 125.4 nm after reaction with IgG.
Ku
Benjamin Y
BY
Department of Mechanical and Aeronautical Engineering, University of California, Bainer Hall, 1 Shields Ave., Davis, CA 95616, USA.
Chan
Mei-Lin
ML
Ma
Zhiya
Z
Horsley
David A
DA
Appl Opt. 1997 Feb 1;36(4):903-20
18250756
Proc Natl Acad Sci U S A. 2000 Dec 19;97(26):14268-72
11121032
J Chem Phys. 2005 Oct 8;123(14):144915
16238432
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 1):031404
11909054
J Appl Phys. 2012 Oct 15;112(8):84701
23152643
Nanotechnology. 2006 Feb 28;17(4):S34-47
21727352
Lab Chip. 2006 Jan;6(1):24-38
16372066
J Immunol Methods. 2006 Jul 31;314(1-2):21-9
16842813
J Protein Chem. 1988 Apr;7(2):165-71
3255367
J Mol Biol. 1993 Jun 5;231(3):698-710
8515446