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posted by mattie_p on Saturday February 22 2014, @10:28AM   Printer-friendly
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: 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 []: 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 []).

    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.

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