Slashdot Mirror
Cornell NEMS device Weighs a Single DNA Molecule
karvind writes "Cornell researchers have refined their NEMS device to detect a single DNA molecule and can even count the number of DNA molecules attached to a single receptor by noting the difference in mass. The researchers used the Cornell Nanoscale Facility to create arrays of tiny cantilever oscillators 3 to 5 microns long and 90 nanometers thick on silicon chips. The principle underlying the mass-detection devices is that the frequency at which a solid object vibrates varies with its mass. In the reported experiments, the change in mass of 1 attogram was enough to shift the frequency of vibration by 50 Hz or more, depending on the size of the oscillator. This allowed the researchers not only to detect the binding of DNA molecules, but also to count the number of molecules attached to a single receptor by the total frequency shift. Results are reported in the latest issue of Nano Letters. " (Here's an earlier Slashdot story about weighing molecules by Caltech Researchers.)
From the Cornell Nanoscale Facility, though I don't work there, I'm studying in the attached atrium.
:-)
Woo
The CNF deviated from the typical Cornell naming convention.
CUUAV -> CU Underwater Autonomous Vehicle
CUAUV -> CU Autonomomous Air Vehicle
CUSeeMe -> CU See Me
Hrmm, what would they call a place at Cornell that researches Nanotechnology?
I'm not trolling, because I really want to know. How can we benefit from being able to weigh things that small? I always assumed that stoichiometry was there to get around having to weigh very very small things.
Stand on the weight scale and try and measure your body mass, while all the scientists scream
...the DNA molecule in question had two X chromosomes. The experiment didn't produce any meaningful results because the scientists' lab time was wasted up by a massive argument that started after the molecule asked "does my bum look big in this?"
It would be interesting, therefore, to know if you can get a feel for the variance in the DNA makeup by measuring the varince in mass from the expected value. It would certainly be quicker than mapping each strand out in turn.
Or would that be doing something useful with this technology, rather than just showing off?
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
The device is 3-5 microns wide, which is "micro". But it's 90 nanometers thick, which is "nano". So is a device's scale magnitude named for its "smallest" feature, when it's smaller than "mesoscale" (1 meter), and for its largest, when larger? And since we've been saying "micrometer" too long, so we say "micron" instead, can we start saying "nanon" already? What will we call an orbital solar collector (especially if it's also a "positive fuelcell") that's 10 nanons thick, but 10Km across - nanotech, or megamachine?
--
make install -not war
Background: Molecules vibrate at distinctive frequencies as limited by their bonds and as decided by their atomic weights. The higher the temperature, however, the faster the frequency of vibration. Once the temperature goes high enough, the atoms are vibrating so energetically that they may separate from the molecule they are currently attached to, beginning a chemical reaction.
Their measurement technique appears to use the frequency shift of a laser of a known frequency passing (through?) the material being measured to an array of detectors that each detect a different frequency. The shift in frequency from the original as caused by the molecule then determines the weight.
So, is the measurement dependent on an exact lab controlled temperature, or can a measuring device work in environments where the temperature may vary?
Specifically, could the device already be implanted in the bloodstream to accurately detect specific viruses or cancer DNA by weight, or would it need more work to adjust for temperature variations?
Also, I might as well ask, is bombarding DNA with lasers harmful?
This is easy. Haven't you ever weighed a dog?
Step 1: Step on scale. Record your weight.
Step 2: Step on scale *carrying one DNA molecule*. Record collective weight.
Step 3: Subtract.
--riney
This same technique has been used with AFM (Atomic force microscopy) for a few years. The idea for a sensor is that you introduce a sample and you can tell if your target analyte is present. Specificity is achieved by using an antibody or other type of probe on the oscillator tip... These are a very common type of sensor, but usually a bunch of molecules are required to get a measurable frequency shift. Different ways of measuring frequency, including laser deflection, piezoresistors, and other assorted optical techniques, can be used. Nano-and even micro cantilever technology is cool because it facilitates label and reagent free sensors, with the holy grail of biosensors being a real time, label free, robust, multianalyte sensor with great sensitivity and selectivity over a huge dynamic range. O yeah... and cheaper and faster than Mass Spec. This type of sensor could theoretically do all of these things.
-Adam