Microscopy News Round Up - 50nm Resolution with White Light, Sharpest Manmade Object, Better Multiphoton Signal Collection

Microscopy News Round Up - 50nm Resolution with White Light, Sharpest Manmade Object, Better Multiphoton Signal Collection from Tissue

50-nm Resolution with White Light

Researchers from the University of Manchester and the National University and Data Storage Institute of Singapore have created a microscope that can image objects as small as 50 nm. This is enough resolution to allow a look inside human cells and at live viruses. Unlike many other approaches to overcoming the diffraction limit of optical microscopy, this method doesn’t require a laser. As detailed in a Nature Communications paper, the researchers used a halogen lamp with a peak wavelength of 600 nm for white-light illumination. Microsphere superlenses placed on top of the object surface superlenses magnify the underlying near-field object information up to 8 times, forming virtual images in the same orientation as the objects in the far field. The near-field object information then enters a conventional ×80 objective lens. The researchers believe that they will be able to image objects smaller than 50 nm since, theoretically, there is no limit on the microscope’s resolution. 

Sharpest Manmade Object

Researchers at Canada’s National Institute for Nanotechnology and University of Alberta are also breaking records. They recently made it into the Guinness Book of World Records for the sharpest man-made object. They made a tip used in electron microscopes that is only one atom at its end point. It is made of Tungsten and fabricated using a patented controlled etching method. "We did not start out to set a world record; we were trying to make a better tool for our research," said team leader Robert Wolkow. "Having a world record is a fun achievement, but we are really interested in commercializing this product." The sharp tip is currently being evaluated for its commercial potential in improving electron microscopy.

See the Guinness Book entry here.

Better Multiphoton Signal Collection from Tissue

Researchers at the National Institutes of Health have developed what may be a better way to image tissue with multiphoton fluorescence microscopy. Scientists often use multiphoton microscopy to image deep in tissue, but microscope objectives only capture a small fraction of the light emitted from the technique’s selective excitation of fluorescence of a tightly focused spot. The researchers had previously shown that in tissue blocks, they could improve the signal ~8 fold by collecting light emitted around the excitation spot using parabolic mirrors and condensers. Now, they’ve published a paper in the Journal of Microscopy in which they used a similar method to image living issue. Their in vivo total emission detection (epiTED) instrument incorporates an add-on parabolic mirror external light collection system and makes noncontact images from outside of living tissue. Their simulations suggest that the system could provide a ∼4-fold enhancement, depending on the objective lens, the imaging depth and the sample characteristics. Their initial prototype showed 2-fold improvement in signal collection when imaging a mouse brain, skeletal muscle, and a rat kidney, using a various fluorophores. The images of a rat kidney show the contributions of the parabola (right), calculated objective contributions (middle), and the combined total epiTED system (left) to the total signal detected in vivo. Image reprinted from the Journal of Microscopy.

You may also like to get Enrico Gratton’s take on the work by reading a related Perspectives article in Science.

Coffee Break Moment…

Browsing through the 2010 Science and Engineering Visualization Challenge Winners is a great way to take a break. This is the eighth year for the contest, which is co-sponsored by Science and the U.S. National Science Foundation. You’ll find a slide show, articles, and a podcast at www.sciencemag.org/special/vis2010/.