Caltech Researchers Weigh Individual Molecules

karvind writes "PhysOrg reports that physicists at the California Institute of Technology have created the first nanodevices capable of weighing individual biological molecules. This technology may lead to new forms of molecular identification that are cheaper and faster than existing methods, as well as revolutionary new instruments for proteomics. The Caltech devices are 'nanoelectromechanical resonators' -- essentially tiny tuning forks about a micron in length and a hundred or so nanometers wide that have a very specific frequency at which they vibrate when excited. Slashdot covered earlier the effort by Cornell for measuring attogram objects which also employs NEMS cantilevers."

Finally!

[InternationalCow]

Now we can really measure how many angels can fit together on a pinhead! More seriously, this technology opens up interesting possibilities for high-througput easy mutation screening. Base substitutions (mutations) in a given stretch of DNA will obviously alter its weight. In this way you can easily (well, relatively speaking) detect the presence of a mutation, after which you can select the stretch of DNA that the mutation is in for sequence analysis. It'd be an interesting application for us geneticists.

Resolution

[lachlan76]

In their experiments this represents about thirty xenon atoms-- and it is the typical mass of an individual protein molecule

If they can resolve down to one protein mass, then wouldn't that imply that at this point they can not find the difference between molecules?

Re:Finally!

[tanverenzo]

If you had RTFA, then you would have found that the machine is not precise enough to measure SNPs (single nucleotide polymorphisms) in DNA--a common cause of or marker for many genetic disorders (sickle cell anemia immediately comes to mind). Indeed, the mutation would have to be extreme (spanning 100s of nucleotides) for there to be an appreciable weight difference. And even if the DNA were that damaged, its corresponding protein would be misshaped enough for scientists to pick up.

Re:Cool tech. Some issues

[tanverenzo]

Since E=mc^2, m=E/c^2 Thus, a chemical bond (a storehouse of potential energy) can contribute to the mass of a molecule. The more "energetic" the bond, the more energy it stores, and hence the more mass it has to contribute to the overall molecule. Since, some bonds (and hence configurations) are more "energetic" than others then different configurations result in different overall masses for the same molecule. However, the contribution of mass is so small (by a factor of 1/c^2), it greatly diminishes (relatively) as the size of the molecule increases. Since this weighing machine can only detect the mass of a molecule greater than the equivalent of 30 xenon atoms, the configuration of the molecule doesn't make too much of a difference.