Researchers harness photobleaching effect in photoacoustic imaging effectively

Jan. 16, 2014
Researchers at the School of Engineering & Applied Science at Washington University in St. Louis have found a way to use the photobleaching effect to their advantage when using photoacoustic microscopy to take a close look at biological tissue.

Researchers at the School of Engineering & Applied Science at Washington University in St. Louis (Missouri), led by biomedical engineering professor Lihong Wang, Ph.D., have found a way to use the photobleaching effect to their advantage when using photoacoustic microscopy to take a close look at biological tissue. The work also could be useful in early cancer detection.

Related: Photoacoustic tomography is ready to revolutionize

Related: Deep down and label-free: Bioimaging with photoacoustics

The laser beam used in photoacoustic microscopy measures 200 nm wide. However, the center of the laser beam is so strong that it bleaches the center of a tissue sample. When researchers pulse the laser beam on the tissue, the molecules no longer give signals packed with information. Then, a second laser pulse probes the molecules that are left in the boundary of the sample; in this pulse, the molecules in the center of the sample provide a weaker signal because they are already bleached.

"Previously, when a molecule was prone to bleaching, researchers didn't want to use it because they couldn't get enough information from it," explains Junjie Yao, Ph.D., a postdoctoral research associate in Wang's lab. "Now for us, that is good news."

Melanoma cells (top) and rose petal epidermal cells (bottom) using conventional photoacoustic microscopy (PAM) (left) and photo-imprint photoacoustic microscopy (right). The resolution is considerably sharper in the photo-imprint PAM image. (Image courtesy of the School of Engineering & Applied Science at Washington University in St. Louis)

Wang and Yao subtracted the boundary area of the sample, leaving only the center--or what they call a photo imprint--now down to 80 nm wide, providing a super-resolution image. A smaller diameter of the center provides a better resolution in the image. Yao says that by shrinking that detection spot, it enables them to see a lot of subcellular features, such as mitochondria or cell nuclei.

After each area of the sample is scanned, the researchers create an image. With previous photoacoustic microscopy imaging, the microspheres on the image were blurry. However, with the new photo-imprint photoacoustic microscopy technique, the resulting image is clear and sharp.

Those working in imaging could apply this method to their own research, Yao says.

Full details of the research team's work appear in the journal Physical Review Letters; for more information, please visit http://prl.aps.org/abstract/PRL/v112/i1/e014302.

-----

Follow us on Twitter, 'like' us on Facebook, and join our group on LinkedIn

Subscribe now to BioOptics World magazine; it's free!

About the Author

BioOptics World Editors

We edited the content of this article, which was contributed by outside sources, to fit our style and substance requirements. (Editor’s Note: BioOptics World has folded as a brand and is now part of Laser Focus World, effective in 2022.)

Sponsored Recommendations

Request a quote: Micro 3D Printed Part or microArch micro-precision 3D printers

April 11, 2024
See the results for yourself! We'll print a benchmark part so that you can assess our quality. Just send us your file and we'll get to work.

Request a free Micro 3D Printed sample part

April 11, 2024
The best way to understand the part quality we can achieve is by seeing it first-hand. Request a free 3D printed high-precision sample part.

How to Tune Servo Systems: The Basics

April 10, 2024
Learn how to tune a servo system using frequency-based tools to meet system specifications by watching our webinar!

Precision Motion Control for Sample Manipulation in Ultra-High Resolution Tomography

April 10, 2024
Learn the critical items that designers and engineers must consider when attempting to achieve reliable ultra-high resolution tomography results here!

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!