Femtosecond Laser Shatters Viruses

wattrlz writes "In a development reminiscent of nineteenth century pseudo-science, the father-son team of Kong Thon and Shaw Wei Tsen recently demonstrated that the tobacco mosaic virus can be destroyed in vitro by nano-scale mechanical resonant vibrations induced by repeated ultra-short pulses from a laser. The total energy required is reportedly far below the threshold for human tissue damage and the technique should generalize to human pathogens. Cleaning stored blood is one obvious application."

Danger of re-self-assembly and evolution?

[G4from128k]

First, This will only work if the resonance breaks the bonds inside the proteins that create the subunits that self-assemble into the viral capsids. If the resonance only separates the weakly-bound subunits, then the resulting fragments will tend to re-self-assemble into whole viruses again. To use a bricks and mortar analogy -- if the device only breaks the mortar, the bricks can reused. The trick is to break the bricks.

Second, this solution requires a specific pulse frequency for each virus. It's not a broad-spectrum disinfectant. That suggests that viruses can easily evolve to defeat the device. Mutants that add a few non-functional amino acids to their capsid protein chains or that decorate the capsid surface with different biochemical groups would change the resonant frequency and allow mutants to escape and breed. One can even imagine evolution selecting for viruses that have inherent damping so that no resonant frequency can build enough energy to disrupt the shell. For example, a virus might become effectively heterozygous so that its shell is randomly constructed of two slightly different subunit sequences. A capsid that is not perfectly crystalline would lack a strong resonant frequency and escape disruption.

Overall, this looks like a very promising weapon in the on-going arms race against viruses.

i read the fucking article, it is crap!

[someone1234]

"This technique will be very useful to disinfect all the viruses, known or unknown," Tsen said. "This will make blood transfusion very safe."

Do you see the BS? They say here: UNKNOWN. Lets suppose, you can calibrate the laser against a known virus without harming human cells/tissue/whatever. How do you calibrate this magic laser to several unknown viruses at the same time?

Why This Can Work Without Killing the Host

[SwordsmanLuke]

There seems to be a lot of people here confused on how this laser can destroy the virus without harming the host cells. Please allow me to explain the natural wonder that is "Natural Harmonic Frequencies".

First, imagine pushing someone on a swing. If you want to make the swing go higher, you have to push it just as it starts to swing forward. That way, the swing's energy is increased by the amount of your push, while still getting the full benefit of it's stored potential energy, and Hey, Presto - the swing goes higher. Because of the way swings (and wave energy functions of most sorts) work, the time between each optimal push remains the same. This is the key.

Imagine a sine wave. If you view the wave at the right frequency - every PI units - you'll see the same value. If you were somehow pushing on the wave at those points, you would be changing the amplitude of the function by the same amount every time. If, however, you view the wave at the wrong frequency - say, every 1 unit - you'll get a different section of the wave each time. Over time your pushes will cancel each other out in this case.

Now, if you push enough kinetic energy into pretty much anything, you create a short-lived wave within it as the energy which has not yet been absorbed or lost in some manner reflects back and forth within the structure. Imagine water sloshing in a tub or a building swaying in an earthquake. The speed at which this wave moves back and forth across the structure is the structure's natural resonant (or harmonic) frequency. This is what is being taken advantage of by this pulsed laser.

By firing this laser at the same frequency that the virus happens to vibrate at, a wave is set up in the virus. Since the laser's pulse comes again at the optimal "pushing" time, the amplitude of the vibration increases. Other cells are being vibrated by the laser as well, but because their natural harmonics are different, the pulses cancel themselves out in those cells and they're fine. The targeted virus however, vibrates harder and harder until it literally shakes itself apart.

In recent years, determining the natural harmonic frequencies of large structures has become an important part of engineering. More than one large structure has been destroyed by seemingly insignificant forces which just happened to be coming at the right frequency!

See this [wikipedia.org] for more mathematical details

Re:i read the fucking article, it is crap!

[Paris_Hojo]

I interpreted "known or unknown" to mean the known or unknown presence of a known virus. For example, maybe it's known that this blood donor had AIDS. So they blast the bag with AIDS-killing frickin laser beams. All well and good, but suppose they don't know what other viruses are present? Maybe the donor had the flu? Maybe the donor had HPV? Rather than spending the money to test and run down any number of viruses that may be present in the blood just zap the baggie for AIDS, zap it again for influenza, zap the sonofabitch again for HPV...etc (g'n'r...too obscure?) So that may be what they meant by "known or unknown" viruses...but hey, at least you didn't come to a hasty conclusion and embarrass yourself trying to appear smart.

Other uses?

[blacklagomorph]

Even if there is no way to use this method to destroy viruses without damaging other cells couldn't this be used as a way to sterilize objects?

One virus. Two viruses.

[AP31R0N]

One virus. Two viruses.

The urge to say virii, is hypercorrection. Which is to say... wrong.

But don't take my word for it:
http://en.wikipedia.org/wiki/Hypercorrection [wikipedia.org]
http://en.wikipedia.org/wiki/Plural_of_virus [wikipedia.org]
http://linuxmafia.com/~rick/faq/plural-of-virus.html [linuxmafia.com]
http://homepages.tesco.net/J.deBoynePollard/FGA/plural-of-virus.html [tesco.net]

So unless you are trying to be cute, the plural of virus is viruses.

And know you know!

This is when a stupid person, feeling personally hurt by learning, will whine about language changing over time.