Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 38: Magnetic Particles / Clusters & Biomagnetism

MA 38.9: Talk

Thursday, March 20, 2025, 17:30–17:45, H18

Magnetophoretic distinction of differently surface-functionalized magnetic microparticles by transport in a quiescent liquid — •Yahya Shubbak, Katharina Eichhorn, Nikolai Weidt, Arne Vereijken, Rico Huhnstock, and Arno Ehresmann — Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany

Magnetic particles (MPs) transported in a quiescent liquid close to the surface of a substrate with a periodic magnetic domain pattern is a promising Lab-on-a-chip technology for the detection of MP-bound analytes, even when their size is negligible compared to the MP size. As a proof of principle, we show an all-optical method to distinguish single MPs of the same nominal size that are surface-functionalized with two different chemical groups. More specifically, MPs measuring 2 micrometer in diameter with a polymer coating with only carboxyl end groups (COOH) or a mixture of carboxyl and amino (NH2) groups, respectively, have been studied. Harnessing a variation of liquid-mediated surface interaction forces in our close-to-substrate MP transport scheme, the different MP surface potentials lead to different magnetophoretic mobilities. Accordingly, transport of these MPs in double-distilled water showed a remarkable difference in the average velocity where the COOH MPs were almost twice as fast as the NH2 counterparts. A thorough investigation using external magnetic field pulses of varying durations revealed a significant distinction between both MP species using only moderate flux densities of a few mT.

Keywords: Magnetic Particles; Lab on a chip; Magnetic Substrates; Proteomics; Diagnostics