Controlled cobalt doping in biogenic magnetite nanoparticles

Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

Abstract

Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites.

• Journal Article Type: Article
• Acceptance Date: Mar 25, 2013
• Online Publication Date: Jun 6, 2013
• Publication Date: Jun 6, 2013
• Deposit Date: Jun 8, 2023
• Journal: Journal of The Royal Society Interface
• Print ISSN: 1742-5689
• Electronic ISSN: 1742-5662
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 83
• Pages: 20130134
• DOI: https://doi.org/10.1098/rsif.2013.0134
• Keywords: Biomedical Engineering; Biochemistry; Biomaterials; Bioengineering; Biophysics; Biotechnology; coercivity; Geobacter; anisotropy; Fe(III) reduction; X-ray magnetic circular dichroism; hyperthermia
• Additional Information: Received: 2013-02-11; Accepted: 2013-03-25; Published: 2013-06-06