With the march of the medical research machine yielding ever more imaginative and clever approaches for finding and destroying disease, the use of iron, silver and gold in treatment might seem like a return to the primitive medicines of ancient times. However, the metal-infused medicines now being designed are not the unproven elixirs, potions and tinctures of yesterday's snake oil salesmen, nor today's self-pronounced shaman. They are instead the creations of researchers in labs around the world working to fight diseases including cancer and bacterial infection.


In particular, a very promising area making use of these metals is in the design of medical nanoparticles. Researchers are creating these very tiny particles, 1/50000th the width of a human hair, to facilitate many aspects of medical activity. In particular, these designer particles are being used for disease detection, to enable targeted delivery of drugs and to directly destroy undesirable materials, bacteria and diseased cells. The ability to create such specifically designed materials opens the door to many new medical treatment options that simply did not exist previously.


So what is being done with these metals? Let's break down some of the interesting research by metal type. We'll do this over three articles.


Iron introduced into the body is typically in the form of iron oxide, a form of rust. Researchers at the University of Central Florida have created a nanoparticle with an iron oxide core attached to a fluorescent dye and the vitamin folic acid. When introduced into the body, this combination particle is more heavily absorbed by cancer cells because the cancer cells need high levels of folic acid in order to survive. Once absorbed by the cancer cells in a particular area of the body, these malignant cells can then be seen much more easily with medical imaging equipment.


The magnetic iron core of the particles makes them "visible" to the MRI machines that detect the very small magnetic fields of these particles. At the same time, the attached fluorescent dye shows up brightly under the x-rays of a CT scan or specific laser light that is directed at the tissues. The result of this is essentially that the cancerous cells can be seen much more clearly in the images and the cells can be detected when there are far fewer of them. This improves the chances of detecting and treating the cancer at a much earlier stage, which generally improves the chances of survival. It also allows the progress of treatment to be measured more directly by seeing how many cancer cells are left following a round of treatment.


Now, as designer materials, these nanoparticles can be further enhanced to have more capabilities than most of the gadgets for sale on late night television. The scientists who created the particle with the iron core also tried attaching the commonly used chemotherapy drug Taxol. Again, because of the attached folic acid vitamin, the particle accumulated in the cancer cells to deliver most of the chemotherapy to the cells that deserve it. This leaves other healthy cells with a far lower dose than they would get normally from nontargeted chemotherapy. This is of great benefit in not "killing" the patient to kill the cancer.


In a related bit of research, a similar approach by University of Washington scientists used an iron oxide core and attached to it chlorotoxin, a chemical found in scorpion venom. This venom extract has been researched for more than 10 years as a means of slowing the spread of cancer. When used by itself, the chemical is found to reduce the spread of mice brain cancer cells by 45%. However, when bound to the iron oxide, the researchers found that the combination nanoparticle was able to slow the spread of the brain cancer cells by a phenomenal 98%. The researchers concluded that the particle seemed to prevent cancer cells from elongating and moving between other cells.


Though much effort is targeted at cancer, another area of research using nanoparticles involves elimination of bacterial infection. To this end, biomedical engineers at Brown University have used simple iron-oxide nanoparticles to kill bacterial infections surrounding medical implants. With as many 2.5% of knee implants becoming infected with bacteria and risking the lives of the 500,000 Americans, 70,000 British and 37,000 Canadians having knee replacement annually, the search to find a way to kill the bacteria is very valuable.


What the researchers found, was that injections of the iron oxide nanoparticle at the site of the implant were able to kill 28% of the bacteria over 48 hours and repeated injections over a 6-day period were able to eventually wipe out the bacterial population. As part of the process, the scientists were able to use magnets to pull the particles toward the implant and use MRI to see where the particles were located. Together the different properties of the particle allowed a complete and relatively simple system for elimination of the bacteria.


While all of these efforts with iron oxide nanoparticles are still confined to research labs and are not yet available as general treatment options, the possibilities of these particles seem enormous. Add to this that the iron oxide particle itself is something that that the body can absorb without toxicity and overall, it seems like a pretty powerful medical tool. Of course, further research will be needed to see what happens when these materials are actively working in living bodies instead of only simple cells.


Related Links:


http://news-info.wustl.edu/tips/page/normal/10638.html
http://news.ucf.edu/UCFnews/index?page=article&id=00240041037381429012136c33d79005996
http://en.wikipedia.org/wiki/X-ray_fluorescence
http://www.radiologyinfo.org/en/info.cfm?PG=bodyct
http://uwnews.org/article.asp?articleID=48796
http://www.npr.org/templates/story/story.php?storyId=14024536
http://incredibleortho.com/?page_id=11
http://www.nhs.uk/Conditions/Knee-replacement/Pages/Kneereplacementexplained.aspx
http://news.brown.edu/pressreleases/2009/06/biotechnology
http://secure.cihi.ca/cihiweb/products/2008_cjrr_annual_report_en.pdf

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