Busting Cancer with Iron Oxide Nanoparticles

Iron oxide--already used as an MRI contrast agent--may help physicians treat cancer, according to research by an international team of scientists led by scientists at Rice University and the Methodist Hospital Research Institute in Houston.

A report in the journal Advanced Functional Materials says the researchers embedded iron oxide in silicon mesoporous particles (SiMPS) and discoidal polymeric nanoconstructs (DPNs), allowing them to magnetically track, move, and hold the particles in place. The SiMPs or DPNs can then be heated to kill malignant tumors or trigger the release of drugs.

The scientists were trying to determine how to get iron oxide to find, heat, and kill those cells at the same time, a property not previously possible. They ultimately put thousands of iron oxide particles - with magnetic cores as small as 5 nanometers across - inside larger particles, or "nanoconstructs." These nanoconstructs should fully degrade and leave the body within a few days, they reported.

Researchers around the globe are studying nanoparticles' cancer-finding and -fighting properties.

MIT chemists announced in April that they had found a way to deliver multiple chemotherapeutic agents that reduce side effects of conventional chemotherapy by targeting the drugs directly to the tumors.The triple-threat nanoparticles killed ovarian cancer cells more effectively than particles carrying only one or two drugs; researchers have begun testing the particles against tumors in animals, according to a paper on the nanoparticles published in the Journal of the American Chemical Society.

The MIT scientists hit upon what seems to be a more sophisticated way for delivering the drugs in the particles--engineering the drugs into chemical building blocks that can then be constructed into even greater structures, like chemo-Legos.

In the past, such particles have involved either encapsulating small drug molecules inside the particles or chemically attaching them to the particle. Such methods become increasingly difficult as each new drug is added, and using both methods at once has limitations, according to MIT.

Instead of building the particle and then attaching drug molecules, MIT researcher Jeremiah Johnson created chemical building blocks that already include a drug--joining them together into a specific structure.

Other efforts to attack cancer cells using nanotechnology include the work of Korean scientists,  who inserted tiny robots within genetically modified salmonella bacteria that is attracted to chemicals produced by cancer cells including vascular endothelial growth factor. The microscopic robots, which measure 1 ?m in width, contain capsules with cancer-fighting drugs.

Cornell University researchers have used tiny gold-based particles that could target cancer cells and later be heated up to kill them. MIT engineers also devised nanoparticles to ferry doxorubicin into cancer cells while also delivering gene-therapy agents. Last year, researchers from Harvard developed cancer-fighting nanobots approximately the size of a virus using protein and DNA strands. The bots are cylindrically shaped, enabling them to be stuffed with molecules of cancer-fighting drugs.  

Nancy Crotti is a contributor to Qmed and MPMN.

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