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MA: Fachverband Magnetismus

MA 39: Magnetic Particles

MA 39.11: Talk

Thursday, March 10, 2016, 12:15–12:30, H31

Superparamagnetic Response from Nanoparticles in Splenic Macrophages — •Ulf Wiedwald, Marina Spasova, Anna Elsukova, and Michael Farle — Faculty of Physics and Center for Nanointegration (CENIDE), University Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany

We have identified that murine spleen macrophages harbor an enormous amount of endogenous nanoparticles with monodisperse crystal size and unexpected superparamagnetic properties [1]. It is well established that macrophages contain the 12 nm disk-shaped protein ferritin with an 8 nm cage that can buffer up to 4500 iron atoms in the form of the antiferromagnetic compound ferrihydrite [2]. Although the diameter and iron content identified by transmission electron microscopy support the presence of ferritin, the strong magnetic response is incompatible with the nature of ferrihydrite. We characterized these nanoparticles form splenic macrophages by SQUID magnetometry and found an average magnetic moment of 8600µ_B per particle in the superparamagnetic state at T = 300 K. This indicates the presence of magnetic phases different from the expected antiferromagnetic ferrihydrite. As a result, the intrinsic superparamagnetism of splenic macrophages contaminates cell isolates in magnetic cell separation [1]. This work is a collaboration with the Institute of Experimental Immunology, University of Bonn, Germany.

[1] L. Franken et al., Scientific Reports 5, 12940 (2015).

[2] P. M. Harrison et al., Adv. Inorg. Chem. 36, 449 (1991).

[3] S. Gider et al., Science 268, 77 (1995).