Magnetic nanoparticle chains in gelatin ferrogels: bioinspiration from magnetotactic bacteria

Sebastian Sturm (1) , Maria Siglreitmeier (2) , Daniel Wolf (1) , Karin Vogel (3) , Micha Gratz (4) , Damien Faivre (5) , Axel Lubk (1) , Bernd Büchner (1) , Elena Sturm (née Rosseeva) (2) , Helmut Cölfen (6)

1 IFW Dresden - Leibniz Institute for Solid State and Materials Research
2 University of Konstanz
3 HZDR - Helmholtz-Zentrum Dresden-Rossendorf
4 Saarland University [Saarbrücken]
5 MEM - Microbiologie Environnementale et Moléculaire
6 Department of Colloid Chemistry [Potsdam]

Inspired by chains of ferrimagnetic nanocrystals (NCs) in magnetotactic bacteria (MTB), the synthesis and detailed characterization of ferrimagnetic magnetite NC chain-like assemblies is reported. An easy green synthesis route in a thermoreversible gelatin hydrogel matrix is used. The structure of these magnetite chains prepared with and without gelatin is characterized by means of transmission electron microscopy, including electron tomography (ET). These structures indeed bear resemblance to the magnetite assemblies found in MTB, known for their mechanical flexibility and outstanding mag-netic properties and known to crystallographically align their magnetite NCs along the strongest <111> magnetization easy axis. Using electron holo-graphy (EH) and angular dependent magnetic measurements, the magnetic interaction between the NCs and the generation of a magnetically anisotropic material can be shown. The electro- and magnetostatic modeling demon-strates that in order to precisely determine the magnetization (by means of EH) inside chain-like NCs assemblies, their exact shape, arrangement and stray-fields have to be considered (ideally obtained using ET)

Domaines: Sciences du Vivant [q-bio]; Chimie inorganique

Sebastian Sturm, Maria Siglreitmeier, Daniel Wolf, Karin Vogel, Micha Gratz, et al.. Magnetic nanoparticle chains in gelatin ferrogels: bioinspiration from magnetotactic bacteria. Advanced Functional Materials, 2019, 29, pp.1905996. ⟨10.1002/adfm.201905996⟩. ⟨cea-02308563⟩