Microbial synthesis and the characterization of metal-substituted magnetites

• Published in: Solid state communications 2001-01, Vol.118 (10), p.529-534
• Main Authors: Roh, Y, Lauf, R.J, McMillan, A.D, Zhang, C, Rawn, C.J, Bai, J, Phelps, T.J
• Format: Article
• Language: English
• Subjects: A. Magnetically ordered materials; C. Scanning electron microscopy; C. X-ray scattering; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fine-particle systems; Magnetic properties and materials; Materials science; Nanoscale materials and structures: fabrication and characterization; Physics; Small particles and nanoscale materials; Studies of specific magnetic materials
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/S0038-1098(01)00146-6

The use of bacteria as a novel biotechnology to facilitate the production of nanoparticles is in its infancy. We describe a bacterially mediated electrochemical process in which metal (Co, Cr, or Ni)-substituted magnetite powders were synthesized by iron(III)-reducing bacteria under anaerobic conditions. Amorphous Fe(III) oxyhydroxides plus soluble metal species (Co, Cr, Ni) comprise the electron acceptor and hydrogen or simple organics comprise the electron donor. The microbial processes produced copious amount of nm-sized, metal-substituted magnetite crystals. Chemical analysis and X-ray powder diffraction analysis showed that metals such as Co, Cr, and Ni were substituted into biologically facilitated magnetites. These results suggest that the bacteria may be viewed as a nonspecific source of electrons at a potential that can be calculated or surmised based on the underlying thermodynamics. Microbially facilitated synthesis of the metal-substituted magnetites at near ambient temperatures may expand the possible use of the specialized ferromagnetic particles.