User:Brian P. Josey/Notebook/2010/01/27
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These are my notes from the paper I read on Monday. It is titled, "Mangetoferritin: In Vitro Synthesis of a Novel Magnetic Protein" by Meldrum, Heywood and Mann. The primarily purpose of the paper is to construct magnetoferritin using apoferritin. The paper is fairly short, about a page and a half, and mostly filled with controls and chemical processes that I don't really need.
Ferritin is a protein used to store iron, and consists of two things, a shell and a core. The shell is made out of 24 polypeptide subunites creating a hollow sphere and is called apoferritin. The shell is penetrated by two types of channels, connecting a 8 nm wide inner cavity with the outside of the protein. The core is made from iron oxide ferrihydrite (5Fe2O3·9H2O) and is 6 nm in length.
They were able to generate the cores in the apoferritin by adding iron II, Fe(II) to the apoferritin solution. This created encapsulated crystals that were small enough to fit in the superparamagnetic size range for magnetite. See Monday's notes for an explanation.
Ferrofluids are nano-scale particles of a ferrimagnetic, or ferromagnetic material, that is coated in a surfactant and suspended in a fluid. It therefore has magnetic properties, and will be attracted to a magnet. However, they are not ferromagnetic, but a superparamagnetic, because of the size scale of the particles. They are pretty cool, forming series of spikes when exposed to a field. As Andy explained, it is due to a mixture of domain growth and Laplace pressure. In essence as the particles are attracted to the magnet, surface tension keeps the fluid together, creating the spikes. These fluids have also been used in art before. Sachiko Kodama has created some sculptures, her website is http://www.kodama.hc.uec.ac.jp/index-e.html. Two particularly cool sculptures are "Pulsar" and "Protrude Flow" under the Machinas & Almas link.