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Medicine Science

Janus Particles as Body Submarines? 42

Roland Piquepaille writes "Janus particles, which take their name from a Roman god with two faces, are microscopic 'two-faced' spheres whose halves are physically or chemically different. Now, U.S. researchers have shown that some of these Janus microparticles can move like stealthy submarines when an alternating electrical field is applied to liquid surrounding them. This could lead to new kinds of self-propelling microsensors or means of targeted drug delivery."
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Janus Particles as Body Submarines?

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  • by BadAnalogyGuy ( 945258 ) <BadAnalogyGuy@gmail.com> on Saturday March 01, 2008 @05:27AM (#22608914)
    From the article:

    The application of ac electric fields in aqueous suspensions of anisotropic particles leads to unbalanced liquid flows and nonlinear, induced-charge electrophoretic motion.

    Well, duh. Everyone *already* knew that!
  • Finally! (Score:4, Funny)

    by jovius ( 974690 ) on Saturday March 01, 2008 @06:04AM (#22609016)
    Two faced particles that stealthy move in a liquid. Pick up any government, and you can make the same observation. I wonder if the findings of the research team are applicable to macroscopic solutions?
  • Hmmm (Score:2, Funny)

    But will pilots have to use revealing clothing? After all, that's what turns a mediocre journey into an amaaaazzzing journey.
  • Medical use?! (Score:2, Interesting)

    by Raptoer ( 984438 )

    The electric field was of voltage and frequency similar to the ones you'd get if you plugged a device into a socket in your home or office.

    So what? we have to shock the person for this to work? Yes I know they didn't state the amp requirements, so it could be in the microamp range, but still.

    I can see these particles having uses outside of the medical world, such as a motor with no moving parts that can be scaled down. I cannot however see these having use in medicine, since humans are great big electrical conductors who are also very sensitive to electricity being pumped through them.

    • Re:Medical use?! (Score:5, Insightful)

      by pimpimpim ( 811140 ) on Saturday March 01, 2008 @06:42AM (#22609102)
      Indeed, or the scheme to do the steering of such microamp fields through your body would be so damned complicated that developing this system would be either impossible or overly expensive. And at that point you still haven't thought of a decent take-up mechanism. As I said before, I am ok with Roland Piquepaille giving a shot on popular science articles, but please add some well-thought-through criticism to the PR shit that comes from universities. "Submarine" in-body medicine has been a dream since Asimov wrote about it, but please stop the unreasonable extrapolations from any nano-particle to a submarine that can save us from cancer LOL OMG!

      In the mean time that these people are looking for a problem that fits their solution, a lot of REAL scientific innovation has been going on, e.g. microsensorics and subcutaneous pumps to help diabetes patients in a life-improving way.

  • > spheres whose halves are physically or chemically different

    Sounds like soap. Or the relevant groups grafted on some substrate (dendrimer, cellulose)
    • Re:Soap? (Score:5, Informative)

      by Schiphol ( 1168667 ) on Saturday March 01, 2008 @07:11AM (#22609166)

      Soap molecules are not spherical, really. They are more of like a match, with a lipophobic head and a lipophile body. Now, when they help dissolve fat in water, a number of molecules tend to form spheres, leaving the fat inside, This phenomenon has been exploited for ages to, ehm, wash dishes and the like. Also, a more sophisticated version of this idea has also been around for quite some time: liposomes [wikipedia.org].

      The idea behind TFA is using spheres with two halves. Sort of a dipole that may move around under the effect of an electric field (if I got it right).
  • ...when an alternating electrical field is applied to liquid surrounding them...

    Great news everyone! Now we can take our medicine in our own homes, we just need to climb into the microwave.
  • In the abstract at the bottom, it says that the particles move in a nonlinear fashion. They don't write that it follows a sinusoidal fashion either. My definition of nonlinear is not in a straight line, which would make it difficult to control, especially considering how dynamic the circulatory system is.
    • Air molecules move in a nonlinear fashion. Water molecules move in a nonlinear fashion. People move in a nonlinear fashion in crowds. At a macroscopic level, this doesn't mean hoses (or subways) don't work.

      In certain fields (e.g. audio) "nonlinear" is often used to mean not describable by the function mx + c, but here I think it means that the motion is not describable by a continuous function, which is what you expect of all very small particles in any kind of non-vacuum. Don't they teach Brownian motion n

      • To your hose and subway analogy, both of those are impenetrable boundaries. A water molecule and people can't really move past those boundaries without a lot of energy. You don't really control their velocity or position at a particle level, just contain them.
          The wikipedia article posted below makes it sound even harder to control. Nonlinear functions don't provide a uniform output to a uniform input.
    • This [wikipedia.org] is what they mean.
  • Rather than hope for a front page Ask Slashdot acceptance, I decided to burn a little karma and ask here in a low reply volume discussion:

    Since Friday 29 February, a number of 'net users have experienced odd behavior of discussion forums such as this one. For instance, if the problem still exists here as it does on other boards, this posy WILL NOT HAVE PARAHRAPH BREAKS (all caps to make that stand out in case it does not have said paragraph breaks). Odder still, the breaks show up during composition but not
    • I do. I had to enter manually the paragraph break in my post above, but I saw it unconfigured already when previewing it. That is, I don't think you need to post to make sure the problem remains.
      • Obviously true here on /., but not on some other discussion forums. How odd that a simple formatting issue would affect so many (but not all) users.

        On affected sites, I have used different browsers (Firefox, IE, Opera) and even different machines, all with the same result, as have others.

  • most of the methods for making these particles, which are reported in scientific jounals like Analytical Chemistry or Langmuir (both published by the amer chem soc, abstracts are free) don't use solution phase methods, eg you can make janus particles by coating a monolayer on a planar support.
    untill someone figures out how to make them, it is just a lab curiosity.
    beyond that, janus particles don't really solve the issues (non specific binding, toxicity, plasma half life) for in vivo reporters
  • These researchers had better watch out; what they're doing sounds exactly like the physical mechanism of "electronic paper". The patent enforcers are gonna be all over them when the news gets out about what they're doing. After all, patents were invented to block exactly this sort of "derivative work" based on someone else's earlier inventions.

  • Lack of details! (Score:3, Interesting)

    by flajann ( 658201 ) <fred.mitchell@g[ ]de ['mx.' in gap]> on Saturday March 01, 2008 @11:16AM (#22609832) Homepage Journal
    "The researchers Dr. Orlin Velev, associate professor of chemical and biomolecular engineering at NC State and lead author of the paper; Sumit Gangwal, an NC State graduate student; Dr. Olivier Cayre, a post-doctoral researcher in Velev's lab; and Dr. Martin Bazant from Massachusetts Institute of Technology created tiny two-faced gold and plastic particles and applied low frequency alternating current to the water containing the particles. The electric field was of voltage and frequency similar to the ones you'd get if you plugged a device into a socket in your home or office."

    What galls me is how they "water-down" even the simplest of details, such as what range of frequencies were used to drive the particles. And I fail to understand what that frequency has anything to do with the 50/60 Hz that comes from your wall socket. Maybe I am missing something here. It would be far more informative to see the range -- in exact numbers -- of frequencies used and where they saw the peak performance, where the performance drops off, etc.

    But then, that's my general pet peeve whenever a non-scientist attempts to report on a matter of science. Details are dropped out or distored all over the place. Just to get at even the minimal details I'll have to go to the actual scientifc publications, which, BTW, Eurekalert fails to provide any references or links to.

    So, a bit of lousy reporting if you ask me, on something otherwise truly interesting.

  • by Doc Ruby ( 173196 ) on Saturday March 01, 2008 @12:36PM (#22610194) Homepage Journal
    "Body Submarines"? That doesn't mean some drug, it means a nanothin film I can wear on my body that lets me dive to thousands of meters under the sea!

    AC current flows across the surface of human skin without chemically or physically affecting the human, if cycled at the proper frequencies. Let's see them gin up some hydrophilic/phobic janus particles that can lock together with titanium strength, but contour their shape to the body surface as defined by the AC flows across the skin. Modulating the AC flow pattern to expand out and contract again as we breathe from an air tank. We wouldn't even need special diving NOx mixes, because we wouldn't be pressured anymore into the bends.

    And since the diameter of the "hull" would be only something like a half meter or so, instead of the several meters of submarine ships, we might keep structural integrity to really vast depths at which the relatively cavernous submarine ships would be crushed without internal support, given their surface:volume ratio. It all depends on the physics of the janus particle made for this app.

    And given a thin dynamic surface modulated with AC across the dynamics of our flexible skin, we could even preserve our sense of touch, and even let our noncompressible hairs stick out, so we can feel the water and whatever we touch in it. Though we could selectively armor areas into gloves or other protected areas, again by modulating the AC.

    On land, these sheaths could be invisible body shields, that weigh practically nothing, but redistribute force of incoming blows.

    Science is cool. Science fiction, given the good science, is fun!
  • Hmm, I seem to have put the entire joke in the subject line :)

Always leave room to add an explanation if it doesn't work out.