Making magnetic particles by imitating bacteria

Bacteria might not be able to drive a car or win at game shows, but they know how to make magnetic particles.

Certain strains of bacteria can pull magnetic materials out of their butt, so to speak. And scientists at Ames Laboratory want to imitate it in an effort to make smaller memory or medical devices.

Several strains of bacteria can produce fairly uniform particles of magnetite (three iron atoms, four oxygens) measuring about 50 nanometers across. (A nanometer is a billionth of a meter.) The particles are a natural byproduct of their metabolic system. The crystals in this bacteria are also bound in membranes to form chains. The bacteria use these chains to navigate and orientate themselves to the magnetic field.

Those black things inside the microbe are magnetic particles it is forming. Ames Laboratory

For you and me, producing those particles is more difficult. Ferromagnetic particles can clump in chemical processes, which can reduce the desirable magnetic properties.

The team at Ames (which is funded by the Department of Energy) first identified proteins within the bacteria that create the magnetic crystals and then added polymers to slow down the reaction. Eventually, the group produced synthetic particle chains with properties that were similar to the natural ones. Ames is now trying to create cobalt-ferrite particles. These have interesting commercial properties but aren't made by bacteria.

Bacteria are the factory workers of the future. Several companies are trying to produce fuel by harnessing the metabolism of natural, genetically enhanced and synthetic organisms. Others, such as Cambrios Technologies, are trying to use microorganisms to look for cracks in plane wings and to help produce chips.
 

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