Harnessing microbial subsurface metal reduction activities to synthesise nanoscale cobalt ferrite with enhanced magnetic properties

Coker, Victoria S.; Telling, Neil D.; van der Laan, Gerrit; Pattrick, Richard A.D.; Pearce, Carolyn I.; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard; Lloyd, Jonathan R.

Abstract

Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize
magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe2O4) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of 106 erg cm−3 can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies.

Citation

Coker, V. S., Telling, N. D., van der Laan, G., Pattrick, R. A., Pearce, C. I., Arenholz, E., …Lloyd, J. R. (2009). Harnessing microbial subsurface metal reduction activities to synthesise nanoscale cobalt ferrite with enhanced magnetic properties. Lawrence Berkeley National Laboratory,

• Journal Article Type: Article
• Publication Date: 2009
• Deposit Date: May 22, 2024
• Journal: Lawrence Berkeley National Laboratory
• Peer Reviewed: Peer Reviewed
• Public URL: https://keele-repository.worktribe.com/output/831206
• Publisher URL: https://escholarship.org/uc/item/9975p53b