November 7, 2011 Leave a comment
Researchers have created an explosive composite material using nanoparticles and DNA. Aluminum and copper oxide put together are known to produce energy, but now by using nanoparticles of them their surface area can be increased, and by using DNA to link them together they can be made to self-assemble. DNA exists in organisms in two complementary strands tightly stuck together; these researchers took advantage of this by grafting individual DNA strands onto nanoparticles, mixing them up and letting the complementary DNA strands stick together.
As a result, the complementary strands on each type of nanoparticle bind, turning the original aluminium and copper oxide powder into a compact, solid material which spontaneously ignites when heated to 410 °C (one of the lowest spontaneous ignition temperatures hitherto described in the literature).
If I’m not mistaken, spontaneous ignition here just means that it begins burning (combustion) without being “lit” by a flame or a spark.
In addition to its low ignition temperature, this composite also offers the advantage of having a high energy density, similar to nitroglycerine: for the same quantity of material, it produces considerably more heat than aluminium and copper oxide taken separately, where a significant part of the energy is not released. In contrast, by using nanoparticles, with their large active surfaces, the researchers were able to approach the maximum theoretical energy for this exothermic chemical reaction.
The high energy density of this composite makes it an ideal fuel for nanosatellites, which weigh a handful of kilograms and are increasingly used. Such satellites are too light to be equipped with a conventional propulsion system once in orbit. However, a few hundred grams of this composite would give them sufficient energy to adjust their trajectory and orientation.
The composite could also have a host of terrestrial applications: ignitors for gas in internal combustion engines or for fuel in aircraft and rocket nozzles, miniature detonators, on-site welding tools, etc. Once its heat is turned into electrical energy, the composite could also be used as a back-up source for microsystems (such as pollution detectors scattered through the environment).
This article really caught my attention due, of course, to their use of DNA as a sort of glue. While the article explains why DNA works, and it seems like using DNA to bind nanoparticles is not a new idea, unfortunately it doesn’t explain why DNA is the best choice in this particular case. Double-stranded DNA normally comes apart at temperatures way below 410°C, which seems like it would be relevant here.
In trying to find another article to explain the DNA thing, I found the one I just linked above (and here) about using DNA to form crystal lattices out of nanoparticles; you should check it out. Maybe this line of research will open up nanoparticles for wider use and greater self-assembly, which would probably be pretty revolutionary for all of us.