Dresden 2006 – scientific programme

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.106: Poster

Tuesday, March 28, 2006, 15:15–19:15, P1

Preparation of superparamagnetic ferrofluids for the use in magnetorelaxometry for biological analysis — •Kai Pöhlig, Erik Heim, Wenzhong Liu, Frank Ludwig, and Meinhard Schilling — TU Braunschweig, Institut für Elektrische Messtechnik und Grundlagen der Elektrotechnik, Hans-Sommer-Str. 66, D-38106 Braunschweig, GERMANY

Nowadays, immunoassays are widely used to detect concentrations of biomolecules with specific markers. As markers we use superparamagnetic nanoparticles (SPIOs). SPIOs have the advantages of being non-toxic, that they can be used in opaque medium and that they are suitable for fluid phase assays at the same time. For this method superparamagnetic nanoparticles with 20 nm core diameter with a narrow particle size distribution are needed to obtain relaxation signals with high amplitude and high signal-to-noise ratio. So far, it is not possible to get a commercial monodispersive ferrofluid with these characteristics. For this reason we use commercial ferrofluids with a broad size distribution made of magnetite (Fe₃O₄) or hematite (Fe₂O₃) and extract the desired particle size via magnetic fractionation. For this purpose we use magnetic separation columns. In magnetic fields up to 1 T the ferrofluids are fractionalised. The resulting particle size and size distribution is evaluated by the methods of AFM, TEM and STEM. Additionally, we verify the results with our differential fluxgate magnetorelaxometry system.

Financial support by the DFG via SFB578 is acknowledged.