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Magnetic nanoparticles: what can't they do?

We've already covered the potential use of magnetic nanoparticles in the olive oil industry and now here are two new reports from a single journal just in the last week regarding their applications in the treatment of cancer. A revolution is coming and it is tiny and magnetized.


In the latest paper, scientists have proposed a new multifunctional nanoparticle with a magnetic core and an outer shell of polydopamine. The particles are termed multifunctional because they have more than one function, duh can be used for diagnostics or therapeutics. There is of course a portmanteau for this: theranostic.

Researchers bound a single strand of DNA to the polydopamine exterior of the particle along with a fluroescence tag. As long as the tag was on the nanoparticle, it didn't fluoresce. When the strand of DNA paired up with a matching strand of mRNA in the cell, they dissociated from the nanoparticle and fluorescence was detected. This is a useful diagnostic tool as mRNAs can act as markers to determine the stage of a disease. Additionally, the magnetic cores of the nanoparticles are commonly used to enhance contrast in MRI imaging. Finally, because the polydopamine absorbs near-infrared light (and most bodily tissues do not), the particles can be used for photothermal therapy. That is, once they have accumulated in a tumor cell, IR light can be used to heat them and destroy the cancerous cell.

The work published several days earlier reported a totally different tack for treating cancer with nanoparticles. See, one of the potential dangers of photothermal therapy is damage to the surrounding non-cancerous tissues due to heating. These nanoparticles rely instead on rotational motion to enter cells and destroy them from the inside. Like a nano-Trojan horse.

Researchers found a way, for the very first time, to use a low frequency dynamic magnetic field to cause magnetic nanoparticles to spin about their own axes. Interestingly, the rate of spinning can be controlled for differing purposes. For example, the nanoparticles can be spun slowly when they're on the outer cell membrane so that they sort of "roll" along the membrane in order to find the best access point. Once inside, they can be spun rapidly in order to wreak havoc and destroy the cell. By coating the nanoparticles with particular antibodies, they can even be directed to specific parts of the cell.


Aside from just cell destruction, an alternative application for this sort of work is in releasing trapped drugs. Apparently, up to 40% of a cancer drug dose can be sequestered in cell lysosomes where it is ineffective. These nanoparticles can be targeted to the lysosomes and then spun at the correct rate to puncture them and release the drugs.

Magnetic nanoparticles: they won't just save your olive oil, they might save your life.


Check out the orginal studies:

Multifunctional Fe3O4@Polydopamine Core–Shell Nanocomposites for Intracellular mRNA Detection and Imaging-Guided Photothermal Therapy and Dynamic Magnetic Fields Remote-Control Apoptosis via Nanoparticle Rotation


Image: Georgia Tech, Research News

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