Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nondestructive 3-D imaging of biological cells with sound

23.04.2015

Walailak University and Hokkaido University researchers report the first known full 3-D scan of a single biological cell via picosecond ultrasound, an acoustic imaging technique

Much like magnetic resonance imaging (MRI) is able to scan the interior of the human body, the emerging technique of "picosecond ultrasonics," a type of acoustic imaging, can be used to make virtual slices of biological tissues without destroying them.


These are fluorescence micrographs of fat and endothelial cells superimposed on differential-interference and phase-contrast images, respectively. The nuclei are stained blue in the micrographs. The image on the right is a picosecond-ultrasonic image of a single endothelial cell with approximately 1-micron lateral and 150-nanometer depth resolutions. Deep blue corresponds to the lowest ultrasonic amplitude.

Credit: O. Wright/Hokkaido University

Now a team of researchers in Japan and Thailand has shown that picosecond ultrasonics can achieve micron resolution of single cells, imaging their interiors in slices separated by 150 nanometers -- in stark contrast to the typical 0.5-millimeter spatial resolution of a standard medical MRI scan. This work is a proof-of-principle that may open the door to new ways of studying the physical properties of living cells by imaging them in vivo.

Picosecond ultrasonics has been used for decades as a method to explore the mechanical and thermal properties of materials like metals and semiconductors at submicron scales, and in recent years it has been applied to biological systems as well. The technique is suited for biology because it's sensitive to sound velocity, density, acoustic impedance and the bulk modulus of cells.

This week, in a story appearing on the cover of the Journal Applied Physics Letters, from AIP Publishing, researchers from Walailak University in Thailand and Hokkaido University in Japan describe the first known demonstration of 3-D cell imaging using picosecond ultrasonics.

Their work centers on imaging two types of mammalian biological tissue -- a bovine aortic endothelial cell, a type of cell that lines a cow's main artery blood vessel, and a mouse "adipose" fat cell. Endothelial cells were chosen because they play a key role in the physiology of blood cells and are useful in the study of biomechanics. Fat cells, on the other hand, were studied to provide an interesting comparison with varying cell geometries and contents.

How the Work was Done

The team accomplished the imaging by first placing a cell in solution on a titanium-coated sapphire substrate and then scanning a point source of high-frequency sound generated by using a beam of focused ultrashort laser pulses over the titanium film. This was followed by focusing another beam of laser pulses on the same point to pick up tiny changes in optical reflectance caused by the sound traveling through the cell tissue.

"By scanning both beams together, we're able to build up an acoustic image of the cell that represents one slice of it," explained co-author Professor Oliver B. Wright, who teaches in the Division of Applied Physics, Faculty of Engineering at Hokkaido University. "We can view a selected slice of the cell at a given depth by changing the timing between the two beams of laser pulses."

The team's work is particularly noteworthy because "in spite of much work imaging cells with more conventional acoustic microscopes, the time required for 3-D imaging probably remains too long to be practical," Wright said. "Building up a 3-D acoustic image, in principle, allows you to see the 3-D relative positions of cell organelles without killing the cell. In our experiments in vitro, while we haven't yet resolved the cell contents -- possibly because cell nuclei weren't contained within the slices we viewed -- it should be possible in the future with various improvements to the technique."

So far, the team has used infrared light to generate sound waves within the cell, "limiting the lateral spatial resolution to about one micron," Wright explains. "By using an ultraviolet-pulsed laser, we could improve the lateral resolution by about a factor of three -- and greatly improve the image quality. And, switching to a diamond substrate instead of sapphire would allow better heat conduction away from the probed area, which, in turn, would enable us to increase the laser power and image quality."

So lowering the laser power or using substrates with higher thermal conductivity may soon open the door to in vivo imaging, which would be invaluable for investigating the mechanical properties of cell organelles within both vegetal and animal cells.

What's next for the team? "The method we use to image the cells now actually involves a combination of optical and elastic parameters of the cell, which can't be easily distinguished," Wright said. "But we've thought of a way to separate them, which will allow us to measure the cell mechanical properties more accurately. So we'll try this method in the near future, and we'd also like to try our method on single-celled organisms or even bacteria."

###

The article, "Three-dimensional imaging of biological cells with picosecond ultrasonics" is authored by Sorasak Danworaphong, Motonobu Tomoda, Yuki Matsumoto, Osamu Matsuda, Toshiro Ohashi, Hiromu Watanabe, Masafumi Nagayama, Kazutoshi Gohara, Paul H. Otsuka and Oliver B. Wright. It will appear on the cover of the Journal Applied Physics Letters on April 20, 2015 (DOI: After that date, it can be accessed at: http://scitation.aip.org/content/aip/journal/apl/106/16/10.1063/1.4918275

Authors of this study are affiliated with Walailak University and Hokkaido University.

ABOUT THE JOURNAL

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: http://apl.aip.org

Media Contact

Jason Socrates Bardi
jbardi@aip.org
240-535-4954

 @jasonbardi

http://www.aip.org 

Jason Socrates Bardi | EurekAlert!

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>