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Tuning the magnetic response of magnetospirillum magneticum by changing the culture medium: a straightforward approach to improve their hyperthermia efficiency

Abstract: Magnetotactic bacteria Magnetospirillum magneticum AMB-1 have been cultured using three different media: magnetic spirillum growth medium with Wolfe's mineral solution (MSGM + W), magnetic spirillum growth medium without Wolfe's mineral solution (MSGM-W), and flask standard medium (FSM). The influence of the culture medium on the structural, morphological, and magnetic characteristics of the magnetosome chains biosynthesized by these bacteria has been investigated by using transmission electron microscopy, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism. All bacteria exhibit similar average size for magnetosomes, 40-45 nm, but FSM bacteria present slightly longer subchains. In MSGM + W bacteria, Co2+ ions present in the medium substitute Fe2+ ions in octahedral positions with a total Co doping around 4%. In addition, the magnetic response of these bacteria has been thoroughly studied as functions of both the temperature and the applied magnetic field. While MSGM-W and FSM bacteria exhibit similar magnetic behavior, in the case of MSGM + W, the incorporation of the Co ions affects the magnetic response, in particular suppressing the Verwey (~105 K) and low temperature (~40 K) transitions and increasing the coercivity and remanence. Moreover, simulations based on a Stoner-Wolhfarth model have allowed us to reproduce the experimentally obtained magnetization versus magnetic field loops, revealing clear changes in different anisotropy contributions for these bacteria depending on the employed culture medium. Finally, we have related how these magnetic changes affect their heating efficiency by using AC magnetometric measurements. The obtained AC hysteresis loops, measured with an AC magnetic field amplitude of up to 90 mT and a frequency, f, of 149 kHz, reveal the influence of the culture medium on the heating properties of these bacteria: below 35 mT, MSGM + W bacteria are the best heating mediators, but above 60 mT, FSM and MSGM + W bacteria give the best heating results, reaching a maximum heating efficiency or specific absorption rate (SAR) of SAR/f ? 12 W g-1 kHz-1.

 Fuente: ACS Applied Materials and Interfaces, 2023, 15 (1), 566-577

 Editorial: American Chemical Society

 Año de publicación: 2023

 Nº de páginas: 12

 Tipo de publicación: Artículo de Revista

 DOI: 10.1021/acsami.2c18435

 ISSN: 1944-8252,1944-8244

 Proyecto español: MAT2017-83631-C3-R

 Url de la publicación: https://doi.org/10.1021/acsami.2c18435

Autoría

GANDIA, DAVID

MARCANO, LOURDES

GANDARIAS, LUCÍA

VILLANUEVA, DANNY

ORUE, IÑAKI

MARIUS ABRUDAN, RADU

VALENCIA, SERGIO

RODRIGO, IRATI

GARCÍA, JOSÉ ÁNGEL

MUELA, ALICIA

FERNÁNDEZ GUBIEDA, MARÍA LUISA