Viruses Engineered to Construct Batteries 127
An anonymous reader writes "Researchers at MIT have modified the M13 virus to create very small batteries. With the viruses building wires 6 nanometers in diameter, the research team hopes to 'build batteries that range from the size of a grain of rice up to the size of existing hearing-aid batteries.'"
Environmental disaster looms (Score:4, Informative)
Lemme see here.. (Score:5, Informative)
Second.. it seems unclear that the virus is actually doing any work..
So basically, it seems they're pulling an Auric Goldfinger on those poor viruses, smothering them with conducting gold metal. Seems a bit misleading to characterize that as making the virus produce wire (much less a battery).
Rather, the viruses were modified to form a suitable substrate to cover with metal and turn into a wire, which is something a bit different.
Re:Environmental disaster looms (Score:4, Informative)
details. (Score:5, Informative)
The original article in Science (Score:5, Informative)
um, no! for all sooo many reasons. (Score:1, Informative)
Thats about all the objections for now. Hope that's enough.
Ah, brings back the memories... (Score:5, Informative)
Here's some background for the interested:
M13 is a filamentous bacteriophage. It infect E. coli bacteria and creates a latent infection where the E. coli ends up pumping out hundreds of new M13. Unlike most bacteriophage, the infection is not lethal to the host. The M13 phage itself is thread-like in structure. At the core is the a circular, single-stranded DNA genome arranged in a linear shape. (imagine grabbing a rubber band at both ends and stretching it out so that it's a very elongated and narrow oval) There are 5 types of coat proteins that then coat and protect this DNA. Here's a link to a decent site about M13: http://www.biosci.ohio-state.edu/~mgonzalez/Micro5 21/Lambda/M13.html [ohio-state.edu]
One, G8P, is present in thousands of copies and coats the DNA in a spiral fashion. A pipe cleaner is a fairly good representation of what the phage looks like. At the ends, the other 4 types of proteins form end caps. On the end that infects bacteria, a protein known as G3P is present in 5 copies and mediates the atachment of the virus and its incorporation into the bacterium for infection. G3P is important because it's fairly exposed at the end of the virus. Also, experimentation over the years has found a 'permissive' region in G3P. A permissive region of the protein structure that is tolerant to the addition of new amino acid sequences that do not badly disrupt the normal protein function. Therefore, one can genetically engineer M13 to put a small chunk of new protein into this site and the virus is still capable of infecting bacteria and replicating. The inserted bit of protein is also known to be exposed at the end of the virus.
M13 is available in commercially generated libraries where tens of millions of randonly generated DNA sequences have been inserted into M13. These 'libraries' are then infected into bacteria and amplified. The resulting phage are then sold to researchers who want to find pecific protein sequences that bind to certain targets. Mostly, these targets are biological in nature. For example - to try and find peptide-based drugs that bind to and inactivate a particular cellular receptor. Here is a link to a commonly used commercial library (I used to use it and I know Belcher's group did too) http://www.neb.com/nebecomm/products/productE8120. asp [neb.com] The link also has lots of pretty pictures and the like about how phage display screening works in more detail that I've got below.
Essentially, what you do is take a substrate of interest, in this case, cobalt oxide and mix it with a sample of the library. You use incubation conditions where regular M13 doesn't stick to the CoO. If any of the library phage stick you know it is probably because those particular phage have a protein insert which binds specifically to CoO. You do a few rounds of binding and washing to get the strongest binders and then sequence the cobalt oxide binding proteins you've recovered.
You can churn out hundreds of sequences this way and start building up a library of proteins very specific to a particular inorganic substrate. You can, for example, create proteins that bind to only platinum versus gold and palladium, cupric oxide versus cuprous oxide, etc. There is even evidence that you can discriminate various sizes of nanoparticles and bind to particular crystalline faces of materials this way. I even heard a rumor a few years back of being able to distinguish p and n-doped