Oxidized magnetosomes in magnetotactic bacteria |
| |
Authors: | Andreas U Gehring Michalis Charilaou |
| |
Institution: | a Institute of Geophysics, ETH Zurich, 8092 Zurich, Switzerland b Laboratory of Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland |
| |
Abstract: | Single domain magnetite particles formed in chain assemblies by magnetotactic bacteria (MTB) are taken as proxy in inferring environmental and Earth's magnetism. The reliable use of magnetosomes in MTB, or their fossil remains (magnetofossils), requires that they are unaffected by oxidation. Here we present experimental data from saturation isothermal remanent magnetization (SIRM) and ferromagnetic resonance spectroscopy (FMR) between room temperature and 10 K, which were applied to detect oxidation in intact MTB. The distinction of non-oxidized from oxidized MTB-assemblies is based mainly on two different characteristic physical properties: (i) the intrinsic Verwey transition in pure magnetite, and (ii) blocking of spins of nano-sized products formed during oxidation at the surface or the interior of the magnetosomes. Suppression of the Verwey transition due to oxidation prevents the shift of the anisotropy axes, which in turn conserves the anisotropic properties at room temperature down to low temperature. The presented methodology assures a distinction between non- and oxidized magnetite assemblies, with pronounced certainty, unlike standard dc methods. |
| |
Keywords: | Ferromagnetic resonance spectroscopy (FMR) Magnetospirillum gryphiswaldense Oxidation of magnetosome Interaction-induced shape anisotropy |
本文献已被 ScienceDirect 等数据库收录! |
|