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."

Comments

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.

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:Finally!

[Frankie70]

Now we can really measure how many angels can fit together on a pinhead!

I am a pinhead, you insensitive clod!!!!

Cool tech. Some issues

[Dancin_Santa]

I was under the impression that at the atomic and molecular level there were quantum phenomena that caused particles to gain and lose mass depending on how they are arranged within the atom/molecule. For example, (just making something up) a molecular bond would result in the total mass of a molecule being less than the sum of the masses of its atoms.

If working with isotopes, it seems feasible to measure the mass of any particular molecule. What were the issues that were blocking this sort of measurement before?

Re:Cool tech. Some issues

[RWerp]

You're right that the bonds make the total mass smaller. But we're talking about stable molecules here, which bonded in one specific way. If their mass were to change, they would have to decay or interact with the environment. If the molecule is stable, it's energy is very well defined. The only limiting factor is the principle of uncertainty, which basically tells here, that the longer you measure the mass, the more precise you are. So the deviation of the measurement may change, but not its expectation value. It would be very interesting, however, if we could apply this -- or other -- technique to measuring masses of unstable molecules and watch how it changes in time.

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.

Re:Cool tech. Some issues

[fearofcarpet]

You're right that the bonds make the total mass smaller. But we're talking about stable molecules here, which bonded in one specific way. If their mass were to change, they would have to decay or interact with the environment. If the molecule is stable, it's energy is very well defined. The only limiting factor is the principle of uncertainty, which basically tells here, that the longer you measure the mass, the more precise you are. So the deviation of the measurement may change, but not its expectation value. It would be very interesting, however, if we could apply this -- or other -- technique to measuring masses of unstable molecules and watch how it changes in time.

Huh? You're going to have to explain to me how you bonds change the mass of a molecule... Especially decreasing it. I'm really curious where you heard this. Perhaps there is some nuance to this statement that I'm missing? Are you saying that the mass of the constituent atoms is different than that of a molecule? This can certianly be true if electrons are gained or lost, but chemical bonds don't affect anything beyond the valence electrons of the atoms. As for uncertainty - I'm not buying it. Even if there was a teeny tiny mass "change" over time, you'd be hard pressed to observe it, especially when you're talking about molecules weighing thousands of Daltons... The difference in scale would be like trying to measure the mass you loose from expelling carbon dioxide while standing on your bathroom scale - and having to take into account mass loss to water evaporation, skin exfoliation, etc. Macromolecules, especially biological molecules, have static charge build up, hydration, aggregation, etc. all contributing to a very dynamic system.

At any rate the "mass of a molecule" is an average of all the weights based on the natrual abundance of isotopes because that is the only factor that affects the mass of two molecules with the same empirical formula. "Unstable" molecuels loose mass by becoming different molecules. It is incorrect to say that a molecule's weight changes - that is impossible (save radioactive decay) because when the empirical formula changes, you no longer have the same molecule.

At any rate, it is an interesting challenge to identify biological molecules by weighing them one at a time, as the horrific isotope distribution in the mass spec of any macromolecule demonstrates.

weigh station

[Lotharjade]

Who will be stuck working the nano-weigh station of the future? Sounds like a crappy job with a Small paycheck.

Nickle-and-Dime

[Renraku]

In other news, these devices are being utilized in the brand new series of gas pumps designed to pump gas throughout the next century.

"We're very excited about this new technology." says an anonymous CEO of a Fortune 500 oil company.

"No longer can the customer get a free $.009 with every purchase. They'll now be billed down to the exact molecule. Its a tough measure, but those freeloaders were really putting a strain on our budgets."

It's true, but...

[Dancin_Santa]

has there been a relatively recent boom in nanotechnology?

They are all really small breakthroughs.

Vibrate when excited?

[Cruithne]

Thats funny... doesnt excitement usually occur because of vibrating, not the other way around? And if this is true, could be devise some sort of perpetual excitement/vibration motion device involving women and 'nanoelectromechanical resonators'? Or perhaps a beowulf cluster of the aforementioned.... *consults the man page for 'woman'* This post a product of SlashPost generator v 0.4.1 alpha build 0138 with SlashClicheMod 2.0

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:Resolution

[operon]

proteins does not have a typical mass. They have a wide range of masses, with molecules having few aminoacids to large and complex quaternary strucutures.

Re:April 1st!!!

[Spad]

Slashdot, where the April Fools jokes get posted on the 3rd of April and again on the 4th.

Fool me once...

[gnovos]

Caltech Researchers Weigh Individual Molecules
Technology
Science
Posted by CowboyNeal on Friday April 01, @01:31AM
from the heavy-lifting dept.

Ha ha ha! I get it, I get it.
"nano" machines, "molecules" "Caltech"

You got me AGAIN! Man, CowboyNeal, you sure pulled the wool over my eyes. Ha ha ha. Whew, that was a good one.

The problem as I see it

[minginqunt]

Is that the problem with this picoscillatory nanoids is that their normal modes have a tendency to reverse the polarity of the neutron flux through the quantum mass matrix.

This has the unfortunate effect that at that point, you have little choice when determining the altoid-dense uberstate discrepancy to assume that the entire universe weighs exactly the same as Cheryl Tweedie from Girls Aloud.

Hooray for physics.

Here we go again....!

[Le_Batleur]

You know, I'm not going to believe one darned word posted today on Slashdot. If anybody has any news they want people to believe, post it tomorrow. Imagine what would happen if the BBC or CNN sprinkled six or seven fake stories into their broadcasts like Slashdot do every year....

There goes the neigbourhood

[tezza]

Your Honour,

The defendant stands charged for posession of with intent to supply, 300 zeptograms of 3,4-methylenedioxymethamphetamine, a Class A prohibited substance under ...

Medical Use

[bobbuck]

Doctors and hospitals need this techology right now so they can weigh patients like Calista Flockhart.

Finally

[aussie_a]

An instrument that can now weigh my penis.

Wait. Did I say that outloud? I guess I better turn off my spam-blocker.

Amazing...

[RobertKozak]

Its just amazing how colored our perception can be of a story.

When I first read it I assumed it was an infamous April 1 slashdot story so each comment I read was biased based on that perception.

I either thought you were an idiot for replying intelligently to this story or that you were extremely witty and sly in your reply and that demonstrated that you got the joke.

But I did something we rarely do and went to read the story and found it was written 2 days ago.

I guess the joke is on me....oh well at least I can read all about it again tomorrow. -- Robert

Mass spectroscopy

[FirienFirien]

This is the next step from a process called mass spectroscopy, where a molecule is given + or - one electron, then fired through a calibrated magnet to hit a target. If the magnet is calibrated so that a single charge on a molecule of weight W deflects by exactly n degrees, then if the molecule weighs W it will hit the target, and you know the mass of your molecule.

It's more trial-and-error than TFA, but with a sweep across the calibration settings you get lovely graphs showing how much of a mixture is which compound. It's fast (seconds for a full-range mass chart), which I somehow doubt TFA is quite up to yet - maybe for a single molecule, but something in the description rankles of a slow process.

Who says Americans don't understand irony?

[panurge]

Posting an absolutely straight story with accurate detail, but which sounds like it might be a fake...on 1st April.

That, my friends who use "irony" when you mean "paradox" or just "contradictory" - that is not only real irony, it's inverted irony. Full marks.

Re:Who says Americans don't understand irony?

[FidelCatsro]

not as bad as people confusing Irony and ironic ,
To explain irony i just quote the dictionary definition
!: contraining or apearing to contain Iron
That my freinds is irony

Re:uhh... so what?

[FirienFirien]

We know the masses of a lot of the atoms (though there's a lot more than 1000 isotopes). Molecules are a completely different matter; there's an infinite range of possible molecules, because you can put them together in a lot of different ways; chain molecules (like DNA (hey, there's 5 billion different molecules - and that's only counting humans!)) are difficult to untangle and sort out; when you can weigh them, you can use the masses of atoms to try to calculate how many of each atom is in the molecule, and from there you can try and work out which configurations of atoms are possible.

Re:uhh... so what?

[mamladm]

As I understand it, one of the more useful applications envisaged for the technique is not to find out what the actual weight of a given molecule is, but to detect the presence of a particular molecule, such as certain proteins which are present in blood in the very early stages of cancer and which are very difficult to detect with today's methods.

I think it's great...

[Godwin O'Hitler]

...that they're naming these new units after stars of the past. After zeptograms we'll no doubt be seeing grouchofarads, chicobytes, and harpohertz.

The joke is...

[DigiShaman]

The joke is that you THINK it's a joke when in fact it's not. Ha ha.

No it's not

[Mr. Underbridge]

It's an April Fool's joke you idiot. Weighing molecules, what idiocy. Like you can make a molecule-sized set of scales to weight it on. Not to mention that molecules don't weight straight down like objects, they float about, so wouldn't press down on the scales. The rest of the article is filled with pseudo-science drivel to try to look clever and hide the fact that they're making the whole thing up.

I'm familiar with his research, half my group collaborated with him, and I think I met him once. It's real. MEMS-based cantilever technology has been getting progressively better, this isn't particularly surprising.

I don't know why you're surprised that New Scientist is pseudoscience, but you can find similar results with real science in journals. Look up Roukes, M in "web of science" or something.

Nice troll, but I can't have you confusing the n00bs on matters scientific.