New Microscope Watches Cells in 3D

Jamie found a story about a new 3D Microscope which creates 3D videos of cells in action. Traditionally scientists have had to choose between high resolution and animation, so no doubt this device will cure the common cold.

Comments

Bad summary...

[ed.mps]

...and bad jokes. A little excerpt for those who didn't RTFA:

It can, for example, capture chromosomes spooling during cell division or a cervical cancer cell shriveling up when treated with acetic acid.

Re:Death by light

[kebes]

Photo-damage to cells is indeed a concern, but the described technique actually has the advantage that this can minimized as much as physically possible. Many visualization techniques involve either (1) having the cell absorb light, so that you can differentiate different regions based on absorption (may require staining with something sufficiently absorptive), or (2) having something fluoresce, which requires that species to absorb and then re-emit light (typically requires staining or genetic engineering so a target protein is fluorescent). Obviously both (1) and (2) require the sample to actively absorb photos, which means that some amount of photo-heating is unavoidable. Moreover fluorescent molecules often lead to undesired side-reactions and degrade over time (so-called "photo-bleaching"). With fluorescence imaging, you can select an excitation wavelength outside of the absorption bands of everything in solution (especially water!), and thereby minimize photo-heating and photo-damage.

The article says that they are actually imaging the refracted light. Since this technique doesn't require any amount of sample absorption at all, they can use a minimally absorbing wavelength, thereby keeping sample damage to an absolute minimum. In fact since they are measuring refracted light, the technique works best at wavelengths where absorption is as low as possible (but refractive index contrast is as high as possible).

From the description, it doesn't sound like the illumination would be much more intense than what a normal microscope generates. Most cells don't experience significant photo-damage under such illumination conditions.

Some current imaging systems use a raster-scanned focused-laser spot to generate the images. By using high-quality detectors the light-levels can be kept low enough that cell damage is prevented. Thus the technique from the article probably induces less cell damage than currently used techniques. Not to mention that the fact that you don't have to stain or modify the cells eliminates the toxicity (or perturbing effect) or those staining agents.