If you’ve seen many old westerns, then you’ll likely have watched a few scenes where one cowboy has to suck rattlesnake venom out of another one’s leg. Things would have been much easier for those cowboys if nanosponges had been around at the time. Developed by scientists at the University of California, San Diego, the tiny sponges mimic red blood cells, and are able to soak up lethal toxins – including snake venom and bacteria – from the bloodstream.
The nanosponges are made up of a biocompatible polymer core, which is coated with segments of the host’s red blood cell membranes. That coating fools the immune system into identifying the sponges as the body’s own blood cells, so it doesn’t attack them. Because each nanosponge is 3,000 times smaller than a red blood cell, the harvested membrane of one cell provides enough material to coat thousands of sponges.
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When injected into the bloodstream, the nanosponges attract “pore-forming toxins,” just like real red blood cells. These toxins are produced not only by snake and insect venom, but also by bacteria such as MRSA (methicillin-resistant Staphylococcus aureus) and E. coli. They kill cells by perforating their outer membranes.
So many of the nanosponges are injected that they end up actually outnumbering the real red blood cells in the bloodstream. This results in the majority of the toxins attaching themselves to the sponges, leaving most of the blood cells alone. Those toxin-laden sponges are then carried to the liver, where both the polymer and the toxins are safely metabolized with no harmful effects to the body.
In lab trials, 89 percent of mice survived lethal doses of alpha-haemolysin toxin from MRSA, if first inoculated with the nanosponges. That figure decreased to 44 percent when the sponges were injected after exposure to the toxin.
One of the other good features of the nanosponges is the fact that in their stock form, they can neutralize a variety of toxins – other anti-toxins must be custom-synthesized in order to absorb specific toxins, with no one substance being effective against such a broad range.
Clinical trials of the nanosponges are now being planned. The project was led by Prof. Liangfang Zhang, and described in a paper recently published in the journal Nature Nanotechnology.
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