Nov 5, 2009 01:17 PM
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Three new therapies that might make their way to hospitals soon show impressive possibilities for changing the way you heal, using lasers and nanotechnology, as well as synthetic skin and superhealing nerve cells.
Nanoboxes
Researchers at Washington University in St Louis have developed tiny gold cubes called nanoboxes which could deliver drugs to precisely targeted areas of the body. How? These boxes only open up and spill their drug contents when exposed to light.
The nanoscale boxes will come packed with a drug, and then release it when hit by a laser. To do this, nanoscale gold boxes are created, and then coated with a polymer called poly(N-isopropylacrylamide). The polymers cling to the outer walls of the cube like hairs on a muppet, and seal the pores on the cube, thus preventing any of the payload from leaking. When the gold is hit by light of a resonant frequency, it absorbs it and converts it to heat, and when the polymer is warmed, it shrinks and collapses, releasing the medicine. Once the light is turned off, the polymers stand on end again, re-sealing the boxes.
According to Dr. Jingyi Chen, one of the principal investigators on the technology, the opening and closing is nearly instantaneous. The nanocubes heat up "from a nanosecond to a femtosecond, [the drugs] are released a little bit slower, that takes around a millisecond." They cool down at the same rate, which allows for extremely fine targeting of dosage. The really cool part is that both the gold and polymer can be fine tuned to work under specific conditions. By thickening the gold walls, the wavelength of light that it can absorb shifts. In this case, they're aiming for the 750-900 nanometer range. Why this wavelength? Because at this point it can penetrate the human body very easily, and can travel inches into the body, as the muscle and blood doesn't easily absorb this wavelength of light. The polymer is then tuned to react to a level of heat that won't kill any cells, but is still above the normal temperature of the body. In trials, the boxes were exposed to a laser of the correct frequency, releasing their dose, and then closing up once the light was turned off. Researchers used the boxes as a way of delivering targeted chemotherapy drugs and antibiotics to a controlled area.
Synthetic Skin
If you're dealing with open wounds, once you flush out any possible bacteria, you need to deal with the realities of closing the flesh. In situations where an injury is over a certain size, it can't be relied on to close normally. Through the use of collagen extracted from skin, doctors can induce new skin to grow by giving it a framework over which to expand. The collagen can be extracted and grown from a variety of sources, such as donated skin, baby's foreskins (apparently up to four football fields worth, which is an utterly disturbing mental image), or from non-human sources, such as mammal organs or reptile skin. The collagen can also be impregnated with other ingredients, such as silver, which is naturally antibiotic. For anything from burns to bedsores, this skin scaffolding can lead to impressive regrowth and healing.
Nerve Regeneration
With spinal injuries, on the other hand, growth is a major problem. The creation of scar tissue around damaged areas of the central nervous system can prevent nerves from healing and regaining function. Previously, the enzyme chrondroitinase ABC (chABC) was used to reduce the scar tissue, but it functioned poorly at body temperature. Within an hour of being injected, it loses half of its potency, and the rest within a few days. Due to this a catheter or pump has to be installed, so that the enzymes can be repeatedly delivered over the two weeks required for it to be effective. Researchers at Georgia Tech have discovered away to reduce the thermal sensitivity of the enzyme, so it can stay in your body effectively for weeks, by bonding the chABC with the sugar trehalose. They also developed a new way to deliver the drug, via an injection of hydrogel filled with microtubes, which allowed deeper penetration than catheters, and slowly releases the drugs over a two week period. This means that the spinal scar tissue can be effectively reduced by a single injection, rather than weeks of constant exposure, and without requiring invasive implants.
Send an email to Tim Barribeau, the author of this post, at tim@io9.com.
Original material is licensed under a Creative Commons License permitting non-commercial sharing with attribution.
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