7 Nature Driven Magnetic Nanoarchitectures
175
for bioremediation, MTB allow recovering the metal from the medium by subsequently trapping the MTB with a magnet.
There are additional nanotechnological applications of magnetosomes not necessarily related to biotechnology. Owing to their uniform shape and size, magnetosomes can be self-assembled forming regularly ordered 2D superstructures [40]
with potential applications as miniaturized high-density data storage materials or
biosensors. Magnetite nanoparticles can be fabricated by a biomimetic approach,
that is, mimicking the MTB biomineralization process in vitro, by using one of the
biomineralization proteins that control the formation of the magnetite crystals within
the cell, namely Mms6 [92]. In this way a novel strategy for the production of magnetic arrays has been reported that involves the fabrication of biotemplates of the
Mms6 with interferometric lithographic patterning, resulting in arrays of uniform
magnetite nanoparticles (86 ± 21 nm) with a period of 357 nm [93]. Finally, magnetosome chains form natural 1D magnetic nanostructures that have inspired the
fabrication of highly anisotropic structures for magnetic field detection in electronic
devices, biosensing or biometric techniques [94].
Although the advantages of magnetosomes and MTB as potential (bio)technological agents are largely demonstrated, the commercial exploitation has not yet been
achieved, primarily because MTB are slow and difficult to culture outside their natural
environment, and also because of the fastidious process needed to extract magnetosomes from the bacteria. Despite advances in scaling up the bacterial production
in large bioreactors for M. gryphiswaldense [95] and M. blakemorei [96], an alternative strategy to overcome this problem comes from instigating the magnetosome
biogenesis in alternative microbes easier to grow in the laboratory. In this sense, gene
clusters of M. gryphiswaldense have been transferred into the photosynthetic bacterium Rhodospirillum rubrum, a microorganism with 90% genetic similarity with
M. gryphiswaldense, and magnetosome biogenesis with a formation of well-ordered
magnetosome chains has been achieved [46]. Magnetosomes bisoynthesized by R.
rubrum are however slightly smaller than those of M. gryphiswaldense and so does
the mass of magnetite per cell.
7.5 Future Perspectives
The field of nanomagnetism is currently a hot topic and the research on magnetotactic
bacteria has definitely a significant role in it. Current challenges in this field include
understanding the biomineralization process towards reproducing the outstanding
magnetite crystals, using magnetosomes as models where to study nanoscale magnetism in a size range hardly reachable by chemical synthesis methods, scale up the
magnetosome production, and optimize the technological potential applications of
magnetosomes and MTB and explore new ones.
175
for bioremediation, MTB allow recovering the metal from the medium by subsequently trapping the MTB with a magnet.
There are additional nanotechnological applications of magnetosomes not necessarily related to biotechnology. Owing to their uniform shape and size, magnetosomes can be self-assembled forming regularly ordered 2D superstructures [40]
with potential applications as miniaturized high-density data storage materials or
biosensors. Magnetite nanoparticles can be fabricated by a biomimetic approach,
that is, mimicking the MTB biomineralization process in vitro, by using one of the
biomineralization proteins that control the formation of the magnetite crystals within
the cell, namely Mms6 [92]. In this way a novel strategy for the production of magnetic arrays has been reported that involves the fabrication of biotemplates of the
Mms6 with interferometric lithographic patterning, resulting in arrays of uniform
magnetite nanoparticles (86 ± 21 nm) with a period of 357 nm [93]. Finally, magnetosome chains form natural 1D magnetic nanostructures that have inspired the
fabrication of highly anisotropic structures for magnetic field detection in electronic
devices, biosensing or biometric techniques [94].
Although the advantages of magnetosomes and MTB as potential (bio)technological agents are largely demonstrated, the commercial exploitation has not yet been
achieved, primarily because MTB are slow and difficult to culture outside their natural
environment, and also because of the fastidious process needed to extract magnetosomes from the bacteria. Despite advances in scaling up the bacterial production
in large bioreactors for M. gryphiswaldense [95] and M. blakemorei [96], an alternative strategy to overcome this problem comes from instigating the magnetosome
biogenesis in alternative microbes easier to grow in the laboratory. In this sense, gene
clusters of M. gryphiswaldense have been transferred into the photosynthetic bacterium Rhodospirillum rubrum, a microorganism with 90% genetic similarity with
M. gryphiswaldense, and magnetosome biogenesis with a formation of well-ordered
magnetosome chains has been achieved [46]. Magnetosomes bisoynthesized by R.
rubrum are however slightly smaller than those of M. gryphiswaldense and so does
the mass of magnetite per cell.
7.5 Future Perspectives
The field of nanomagnetism is currently a hot topic and the research on magnetotactic
bacteria has definitely a significant role in it. Current challenges in this field include
understanding the biomineralization process towards reproducing the outstanding
magnetite crystals, using magnetosomes as models where to study nanoscale magnetism in a size range hardly reachable by chemical synthesis methods, scale up the
magnetosome production, and optimize the technological potential applications of
magnetosomes and MTB and explore new ones.