Harnessing the Extracellular Bacterial Production of Nanoscale Cobalt Ferrite with Exploitable Magnetic Properties
Harnessing the Extracellular Bacterial Production of Nanoscale Cobalt Ferrite with Exploitable Magnetic Properties
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DOI：
10.1021/nn900293d
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发表时间：
2009-07-01
期刊：
影响因子：
17.1
通讯作者：
Lloyd, Jonathan R.
中科院分区：
文献类型：
--
作者：
Coker, Victoria S.;Telling, Neil D.;Lloyd, Jonathan R.
纳米级铁磁颗粒具有广泛的用途，从定向癌症治疗和药物输送系统到磁记录介质和传感器。这种应用需要生产具有良好控制尺寸、成分和磁性质的单分散纳米颗粒。纯粹使用合成方法制造这些材料在环境和经济方面都是昂贵的。然而，金属还原微生物为生产这些材料提供了尚未开发的资源。在这里，铁（III）还原细菌硫还原地杆菌被用来合成磁性氧化铁纳米颗粒。电子显微镜、软x射线光谱学和磁强计技术的结合表明，这种生物合成方法可以获得高产量的晶体纳米颗粒，其尺寸分布窄，磁性能与最好的化学合成材料相当。特别地，这里证明了钴铁氧体（CoFe2O4）纳米粒子的低温矫顽力接近8 kOe，有效各向异性常数类似于10(6)erg cm（-3）。通过在尖晶石结构中引入大量的Co，纳米颗粒的磁性能得到了显著的增强，这比之前利用趋磁细菌在该领域进行的生物矿化研究取得了重大进展。在这项研究中获得的高产量的纳米铁氧体的成功生产可能为使用无害环境的方法扩大纳米颗粒的工业生产开辟了道路。
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 similar to 10(6) 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.