Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > New technique captures chemical reactions in a single living cell for the first time

Lights scatter from metallic nanoplasmonic particles upon excitation of an external light source. UC Berkeley researchers coupled the metallic nanoparticles with biomolecules to detect chemical signals within a single living cell at unprecedented resolution. (Graphic by Gang Logan Liu and Luke Lee/UC Berkeley)
Lights scatter from metallic nanoplasmonic particles upon excitation of an external light source. UC Berkeley researchers coupled the metallic nanoparticles with biomolecules to detect chemical signals within a single living cell at unprecedented resolution. (Graphic by Gang Logan Liu and Luke Lee/UC Berkeley)

Abstract:
Bioengineers at the University of California, Berkeley, have discovered a technique that for the first time enables the detection of biomolecules' dynamic reactions in a single living cell.

New technique captures chemical reactions in a single living cell for the first time

BERKELEY, CA | Posted on November 19th, 2007

By taking advantage of the signature frequency by which organic and inorganic molecules absorb light, the team of researchers, led by Luke Lee, professor of bioengineering and director of UC Berkeley's Biomolecular Nanotechnology Center, can determine in real time whether specific enzymes are activated or particular genes are expressed, all with unprecedented resolution within a single living cell.

The technique, described in the Nov. 18 issue of the journal Nature Methods, could lead to a new era in molecular imaging with implications for cell-based drug discovery and biomedical diagnostics.

The researchers point out that other techniques, such as nuclear magnetic resonance, can at best provide information about a cluster of cells. But to determine the earliest signs of disease progression or of stem cell proliferation, it's necessary to drill down deeper to the molecular dynamics within a single cell.

To study the biochemical processes of a cell, scientists currently cut through its outer membrane to separate and analyze the cellular components. That method can never provide a real-time view of how components function together because the cell is killed in the process of extracting its components.

"Until now, there has been no non-invasive method that exists that can capture the chemical fingerprints of molecules with nanoscale spatial resolution within a single living cell," said Lee, who is also a faculty affiliate of the California Institute for Quantitative Biosciences and the co-director of the Berkeley Sensor and Actuator Center. "There is great hope that stem cells can one day be used to treat diseases, but one of the biggest challenges in this field is understanding exactly how individual cells differentiate. What is happening inside a stem cell as it develops into a heart muscle instead of a tooth or a strand of hair? To find out, we need to look at the telltale chemical signals involved as proteins and genes function together within a cell."

The researchers tackled this challenge by improving upon conventional optical absorption spectroscopy, a technique by which light is passed through a solution of molecules to determine which wavelengths are absorbed. Cytochrome c, for instance, is a protein involved in cell metabolism and cell death that has several optical absorption peaks of around 550 nanometers.

The absorption spectra of a molecule can change based upon the chemical changes that occur as it interacts with other molecules, such as oxygen.

"For conventional optical absorption spectroscopy to work, a relatively high concentration of biomolecules and a large volume of solution is needed in order to detect these subtle changes in frequencies and absorption peaks," said Lee. "That's because optical absorption signals from a single biomolecule are very weak, so you need to kill hundreds to millions of cells to fish out enough of the target molecule for detection."

The researchers came up with a novel solution to this problem by coupling biomolecules, the protein cytochrome c in this study, with tiny particles of gold measuring 20-30 nanometers long. The electrons on the surface of metal particles such as gold and silver are known to oscillate at specific frequencies in response to light, a phenomenon known as plasmon resonance. The resonant frequencies of the gold nanoparticles are much easier to detect than the weak optical signals of cytochrome c, giving the researchers an easier target.

Gold nanoparticles were chosen because they have a plasmon resonance wavelength ranging from 530 to 580 nanometers, corresponding to the absorption peak of cytochrome c.

"When the absorption peak of the biomolecule overlaps with the plasmon resonance frequency of the gold particle, you can see whether they are exchanging energy," said study co-lead author Gang Logan Liu, who conducted the research as a UC Berkeley Ph.D. student in bioengineering. "This energy transfer shows up as small dips, something we call 'quenching,' in the characteristic absorption peak of the gold particle."

A relatively small concentration of the molecule is needed to create these quenching dips, so instead of a concentration of millions of molecules, researchers can get by with hundreds or even dozens of molecules. The sensitivity and selectivity of the quenching dips will improve the molecular diagnosis of diseases and be instrumental in the development of personalized medicine, the researchers said.

The researchers repeated the experiment matching the protein hemoglobin with silver nanoparticles and achieved similar results.

"Our technique kills two birds with one stone," Lee said. "We're reducing the spatial resolution required to detect the molecule at the same time we're able to obtain chemical information about molecules while they are in a living cell. In a way, these gold particles are like 'nano-stars' because they illuminate the inner life of a cellular galaxy."

Other researchers on the UC Berkeley team are Yi-Tao Long, co-lead author and postdoctoral scholar in bioengineering; Yeonho Choi, a Ph.D. student in mechanical engineering; and Taewook Kang, a postdoctoral scholar in bioengineering.

The Ministry of Science and Technology in Korea helped support this research.

####

For more information, please click here

Contacts:
Robert Sanders

(510) 643-6998

Sarah Yang

(510) 643-7741

Copyright © University of California, Berkeley

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Nanomedicine

European Technology Platform for Nanomedicine and ENATRANS European Consortium Launch the 2nd edition of the Nanomedicine Award: The Award to be presented at BIO-Europe conference in Munich, November 2015 July 30th, 2015

Take a trip through the brain July 30th, 2015

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Discoveries

Take a trip through the brain July 30th, 2015

This could replace your silicon computer chips: A new semiconductor material made from black phosphorus may be a candidate to replace silicon in future tech July 30th, 2015

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Announcements

Take a trip through the brain July 30th, 2015

This could replace your silicon computer chips: A new semiconductor material made from black phosphorus may be a candidate to replace silicon in future tech July 30th, 2015

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Nanobiotechnology

European Technology Platform for Nanomedicine and ENATRANS European Consortium Launch the 2nd edition of the Nanomedicine Award: The Award to be presented at BIO-Europe conference in Munich, November 2015 July 30th, 2015

New computer model could explain how simple molecules took first step toward life: Two Brookhaven researchers developed theoretical model to explain the origins of self-replicating molecules July 28th, 2015

Spintronics: Molecules stabilizing magnetism: Organic molecules fixing the magnetic orientation of a cobalt surface/ building block for a compact and low-cost storage technology/ publication in Nature Materials July 25th, 2015

Programming adult stem cells to treat muscular dystrophy and more by mimicking nature July 22nd, 2015

Research partnerships

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Spintronics: Molecules stabilizing magnetism: Organic molecules fixing the magnetic orientation of a cobalt surface/ building block for a compact and low-cost storage technology/ publication in Nature Materials July 25th, 2015

Stretching the limits on conducting wires July 25th, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project