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posted by mattie_p on Saturday February 22 2014, @10:28AM   Printer-friendly [Skip to comment(s)]
from the quantum-is-the-new-black dept.

amblivious writes:

"A team from the University of Queensland has demonstrated quantum imaging inside living cells for the first time. They were able to map structures within cells at scales as fine as 10nm, offering a 14% resolution enhancement over coherent light. Conventional optical imaging is limited by diffraction but by generating the photons with a more consistent phase as squeezed light the amount of diffraction can be minimized.

The ability to map living cells at this scale represents a significant breakthrough in imaging. These methods promise to reveal important new levels of cellular complexity and deliver profound benefits to biotech and medical research, and 'confirm the longstanding prediction that quantum correlated light can enhance spatial resolution at the nanoscale and in biology.'"

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  • (Score: 0, Offtopic) by Anonymous Coward on Saturday February 22 2014, @11:05AM

    by Anonymous Coward on Saturday February 22 2014, @11:05AM (#4782)

    How soon before our good buddy Meatfucker can read brain cells?

    • (Score: 1) by nobbis on Saturday February 22 2014, @12:02PM

      by nobbis (62) on Saturday February 22 2014, @12:02PM (#4791) Homepage Journal

      Why is this trolling ?
      Meatfucker was notorious for this, other minds claimed they didn't do it.
      I'd rather see a comment about a future use involving the Culture, than the usual 'will help cure cancer'

      --
      It's easy to look up when your mind's in the gutter
      • (Score: 4, Informative) by Open4D on Saturday February 22 2014, @02:38PM

        by Open4D (371) Subscriber Badge on Saturday February 22 2014, @02:38PM (#4826) Journal

        I'd rather see a comment about a future use involving the Culture, than the usual 'will help cure cancer'

        But it was a first post, by Anonymous Coward, with no good clues as to what the hell it was going on about. Not every geek reads Iain M. Banks and knows about the Culture [wikipedia.org]. A comment about cancer would have been more realistically on-topic.

  • (Score: 5, Informative) by bd on Saturday February 22 2014, @01:25PM

    by bd (2773) on Saturday February 22 2014, @01:25PM (#4812)

    The summary is a bit hard to understand, and - I think - partially wrong. For those of you who want to understand what they did, I will try to explain it in simple terms.

    They made a better version of a photonic force microscope. PFM's work a bit like atomic force microscopes. AFM's use a probe with a fine tip to mechanically scan a sample at atomic resolution. A PFM uses optical tweezers to move around a nano-particle as a probe. That's nice because you can do it inside a living cell.

    The optical tweezers technique works because dielectric nanoparticles will tend to align to the electrical field of a tightly focused light beam. The shape of the electrical field means that the nanoparticle will see a small force that moves it to the center of the focused beam with high precision.

    They basically move the nano-particle to different places in the cell and observe it's motion. Thereby, they learn something about the properties of the cell at that place. The precision, of course, is affected by noise in the light of the tweezer. Because of that they use a light source with low noise.

    A problem is that the quantized nature of photons introduces a fundamental limit to the amplitude noise of your laser beam. This is because you cannot use a lot of photons because you generally don't want to burn your biological sample.

    Now, there are two kinds of noise in monochromatic laser radiation: amplitude noise and phase noise. Interestingly, both are coupled. Using quantum optics, we can exchange phase noise for amplitude noise and vice versa.

    The summary is wrong in saying that they lowered phase noise and increased amplitude noise, they did the opposite, see: http://www.rp-photonics.com/amplitude_squeezed_lig ht.html [rp-photonics.com]. Thereby they could lower the noise floor by some percents, enhancing the resolution in comparison to a PFM illuminated with a simple coherent light source.

    Of course, this was only a demonstrator and they only moved the particle along a linear path. A proper microscope would have to add two more dimensions to actually scan the whole cell.

    • (Score: 2, Interesting) by NovelUserName on Saturday February 22 2014, @06:06PM

      by NovelUserName (768) on Saturday February 22 2014, @06:06PM (#4891)

      From a quick scan of the article, it appears that this technique is frequently used to probe the mechanical environment at very high resolution: i.e. bounce the probe molecule off of the item of interest and see how stiff it is. Since structural scanning relies on moving a single probe molecule over the 3d surface the technique doesn't seem particularly suited to whole cell imaging. It may be very useful for very fine/local structures such as the shape of specific transport channels in the cell membrane, or binding proteins attached to organelles etc.

      • (Score: 3, Interesting) by bd on Saturday February 22 2014, @07:30PM

        by bd (2773) on Saturday February 22 2014, @07:30PM (#4923)

        Well, you are probably correct. Replace "whole cell" with "region of interest".

        I was actually also wrong about them being only able to scan the particle along a line.

        One problem with their technology demonstrator right now is that they only know the position of their particle in the x direction. The y and z directions are actually random. This means that their particle took a different, unknown trajectory through the cell for each \alpha-scan.

        To conclusively demonstrate their resolution enhancements by showing a detailed picture of something, they now have to build a proper 3D-PFM. I guess they just wanted to publish something before someone else does.

        • (Score: 1) by NovelUserName on Saturday February 22 2014, @09:15PM

          by NovelUserName (768) on Saturday February 22 2014, @09:15PM (#4956)

          I'm nowhere near an expert in the field, but it sounded like the random motion was utilized as a feature (or at least they could derive useful info from it). Basically their apparatus could detect the motion and use that to identify the mechanical properties of the environs.

          • (Score: 1) by bd on Saturday February 22 2014, @10:32PM

            by bd (2773) on Saturday February 22 2014, @10:32PM (#4985)

            They only tracked the particle in the x direction in their coordinate system, not y or z.

  • (Score: 1, Offtopic) by ticho on Saturday February 22 2014, @02:33PM

    by ticho (89) on Saturday February 22 2014, @02:33PM (#4824) Homepage Journal

    So, how long before every US airport is equipped with this? After all, terrorists could try to smuggle bombs inside their own cells!

  • (Score: 3) by Open4D on Saturday February 22 2014, @03:00PM

    by Open4D (371) Subscriber Badge on Saturday February 22 2014, @03:00PM (#4830) Journal

    The ability to map living cells at this scale represents a significant breakthrough in imaging. These methods promise to reveal important new levels of cellular complexity and deliver profound benefits to biotech and medical research

    Out of interest, how well or poorly do biologists currently understand cellular complexity? If this technique became practical, would it revolutionize whole fields of research, or just be used in a few specialized areas, or somewhere in between?

    And would it be used directly in a clinical context, or just for generic research?

    • (Score: 4, Informative) by L.M.T. Spoon on Saturday February 22 2014, @04:35PM

      by L.M.T. Spoon (641) on Saturday February 22 2014, @04:35PM (#4866)

      I have been wondering about this too, and so far haven't seen anything particularly revolutionary. A cellular/molecular biologist is very interested in structure and there are many already existing techniques to elucidate it efficiently. For instance, if you are interested in the cytoskeleton you can easily triple-stain the cell for tubulin, actin, and DNA and get good enough resolution to see any significant effect of drugs, mutations, etc. Atomic force microscopes reveal in great resolution the structure of the cellular surface. X-ray crystallography reveals the structure of proteins, ribosomes, etc. DNA and RNA is relatively easy to sequence, and I'm not sure how this new technique would add to that, or to determining epigenetic markers. Organelles are generally large enough to not require such nanoscale imaging.

      All that being said, however, there are certain things that this new technique may be very helpful with. The first thing that comes to my head is imaging pores in the nuclear, cellular, and organelle membranes. Nuclear trafficking, for one, is a very important topic and the behavior of nuclear pores has only recently been studied successfully. These pores are examples of structures that are difficult to extract whole out of the cell without damaging them, their function is changed by very tiny mechanical shifts, and their structure is very conducive to passing nanoparticles through.

      This sort of study would definitely begin as what you call "generic" research, but it definitely has clinical applications.

    • (Score: 4, Informative) by kebes on Saturday February 22 2014, @05:09PM

      by kebes (1505) on Saturday February 22 2014, @05:09PM (#4872)

      If this technique became practical, would it revolutionize whole fields of research, or just be used in a few specialized areas, or somewhere in between?

      My guess is 'somewhere in between'. The technique works using a variant of optically tweezers [wikipedia.org]: where a highly focused laser 'traps' a particle to a specific region of space (the high light-field gradient exerts a force on interfaces in the dieletric properties of materials). These researchers are trapping very small nanoparticles, and using various quantum tricks to make the trapping very local. The idea is that you can raster scan the laser focal spot in 3D, while measuring the motion of the particle (Brownian motion confined to the small region of the optical trap), and thereby reconstruct 'what's going on' in 3D inside any volume (including inside the cell). You can locally measure viscosity, infer the presence and size/shape or cellular structures, etc.

      This is very nice work, but it has a few drawbacks: serially scanning a single particle through a 3D volume is going to be slow (though one can certainly imagine a more sophisticated version that simultaneously moves/tracks many particles). Moreover, one must always worry about how the probe itself is perturbing the structures being studied. A nanoparticle is similar in size to proteins, so it may well be influencing the cell. This is of course similar to most other techniques of imaging cells.

      In fact, it's worth noting that we already have sub-diffraction-limit probes of structures within cells. Another poster mentioned x-ray diffraction, which can indeed probe order down to the molecular-scale (and modern instruments are now able to generate x-ray beams of nanometer-size, and scan these beams around). There are other tricks, like introducing fluorescent dyes, and taking advantage of non-linear optical effects and correlation mathematics to achieve sub-diffraction imaging inside living cells (Fluorescence Correlation Spectroscopy [wikipedia.org]).

      Each of these techniques has its own advantages and drawbacks. So, I would view this new development as adding another valuable tool to the 'cellular imaging toolbox'. It will probably be superior in some cases. More importantly, by combining different imaging tools (which each perturb the sample in different ways), one can gain much higher confidence about the actual structure within cells.

      would it be used directly in a clinical context, or just for generic research?

      At this point it would only be useful in a research context. It's too complicated and slow for anything else. However, like anything else, one could imagine it being refined and automated to the point that it could be used to routinely measure patient tissue.

      how well or poorly do biologists currently understand cellular complexity?

      This is a bit out of my depth (I'm a physicist, not a biologist!), but there is still much unknown about cellular behavior. For instance, the overall structure is known, and most of the molecules/proteins that are inside a cell have been identified and catalogued. However, most measurements have been done on dead (frozen and sectioned) cells; there is much unknown about the dynamical response of cells. That's why there is so much interest in having methods that can image in 3D inside living cells: to identify how proteins migrate, co-localize, and assemble; to determine how cellular structures respond to external stimuli, etc.

    • (Score: 3, Informative) by lubricus on Saturday February 22 2014, @08:37PM

      by lubricus (232) on Saturday February 22 2014, @08:37PM (#4945)

      Would every cell biologist want one? Probably not. Many cell biologists don't even use eletron or confocal microscopy, instead working with introduced fluorescent proteins, sometimes with simple compound microscopes. It depends on the level of the problem... This is one of the most amazing things about biology, there are so many levels to study, from individual DNA bases, to the structure of tangled DNA, , to individual proteins, to the movement of organelles in the cell, etc. This represents a breakthrough at a specific size scale, which could have implications on other processes (let's say you are studying microtubule formation and you discovery the the mechanism of trisomy), but it won't revolutionize all of biology any more than electron microscopy or confocal microscopy. Also, although I wouldn't rule it out, I can't see any clinical use for this (although IANAMD: I am not a medical doctor). Again, look to where electron microscopy is currently used, and those are the applications that will benefit.

      --
      ... sorry about the typos