Spectral microscopy captures metal-labeled neurons in 3D, and with unprecedented detail

A team of researchers from the University of Minnesota (Minneapolis) and Agnes Scott College (Decatur, GA) used spectral confocal microscopy to image tissues impregnated with silver or gold. Rather than relying on the amount of light reflecting off metal particles, the process involves delivering light energy to silver or gold nanoparticles deposited on neurons and imaging the higher energy levels resulting from their vibrations, known as surface plasmons.

Related: Towards noninvasive detection of diabetic neuropathy

This technique is particularly effective as the light emitted from metal particles is resistant to fading, meaning that decades-old tissue samples achieved through other processes, such as the Golgi stain method from the late 1880s, can be imaged repeatedly. The researchers' achievement involves a laser scanning confocal microscope (LSCM) for spectral detection.

Paired with such methods, silver- and gold-based cell labeling is poised to unlock new information in a myriad of archived specimens. Furthermore, silver-impregnated preparations should retain their high image quality for a century or more, allowing for archivability that could aid in clinical research and disease-related diagnostic techniques for cancer and neurological disorders.

"For the purposes of medical diagnostics, older and newer specimens could be compared with the knowledge that signal intensity would remain fairly uniform regardless of sample age or repeated light exposure," says contributing author Karen Mesce from the University of Minnesota. "With the prediction that superior resolution microscopic techniques will continue to evolve, older archived samples could be reimagined with newer technologies and with the confidence that the signal in question was preserved. The progression or stability of a cancer or other disease could therefore be charted with accuracy over long periods of time."

To appreciate the enhanced image quality produced by the new technique, the team first examined a conventional brightfield image of a metal-labeled neuron within a grasshopper's abdominal ganglion, a type of mini-brain that, even at that size, presented out-of-focus structures. They then imaged the same ganglion with the spectral LSCM adjusted to the manufacturer's traditional fluorescence settings, resulting only in strong natural fluorescence and a collective dark blur in place of the silver-labeled neurons.

Silver-impregnated dendrites from an insect motor neuron, captured through spectral confocal microscopy. (Image credit: Grant M. Barthel, Karen A. Mesce, Karen J. Thompson)

However, after collecting the light energy emitted from vibrating surface plasmons in the spectral LSCM, the team obtained spectacular 3D computer images of silver- and gold-impregnated neurons. This holds enormous potential for stimulating a re-examination of archived preparations, including Golgi-stained and cobalt/silver-labeled nervous systems.

Additionally, by using a number of different metal-based cell-labeling techniques in combination with the new LSCM protocols, tissue and cell specimens can be generated and imaged with ease and in great 3D detail. Changes in even small structural details of neurons can be identified, which are often important indicators of neurological disease, learning and memory, and brain development.

"Both new and archived preparations are essentially permanent and the information gathered from them increases the data available for characterizing neurons as individuals or as members of classes for comparative studies, adding to emerging neuronal banks," says co-first author Karen Thompson from Agnes Scott College.

"Just as plasmon resonance can explain the continued intensity of the red (caused by silver nanoparticles) and yellow (gold nanoparticles) colors in centuries-old medieval stained glass and other works of art, metal-impregnated neurons are also likely never to fade, neither in the information they provide nor in their intrinsic beauty," adds Mesce.

Full details of the work appear in the journal eLife; for more information, please visit http://dx.doi.org/10.7554/eLife.09388.

Follow us on Twitter, 'like' us on Facebook, connect with us on Google+, and join our group on LinkedIn

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now
Related Articles

New bioimaging technique offers clear view of nervous system

Scientists at Ludwig-Maximilians University have developed a technique for turning the body of a deceased rodent entirely transparent, revealing the central nervous system in unprecedented clarity....

Fluorescent jellyfish proteins light up unconventional laser

Safer lasers to map your cells could soon be in the offing -- all thanks to the humble jellyfish. Conventional lasers, like the pointer you might use to entertain your cat, produce light by emittin...

Microscope detects one million-plus biomarkers for sepsis in 30 minutes

A microscope has the potential to simultaneously detect more than one million biomarkers for sepsis at the point of care.

Eye test that pairs two in vivo imaging methods may detect Parkinson's earlier

A low-cost, noninvasive eye test pairs two in vivo imaging methods to help detect Parkinson's before clinical symptoms appear.

BLOGS

Neuro15 exhibitors meet exacting demands: Part 2

Increasingly, neuroscientists are working with researchers in disciplines such as chemistry and p...

Why be free?

A successful career contributed to keeping OpticalRayTracer—an optical design software program—fr...

LASER Munich 2015 is bio-bent

LASER World of Photonics 2015 included the European Conferences on Biomedical Optics among its si...

White Papers

Understanding Optical Filters

Optical filters can be used to attenuate or enhance an image, transmit or reflect specific wavele...

How can I find the right digital camera for my microscopy application?

Nowadays, image processing is found in a wide range of optical microscopy applications. Examples ...

CONNECT WITH US

            

Twitter- BioOptics World