Spaser can find metastasized cancer cells in the blood stream and kill them

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A nanolaser known as the spaser can serve as a super-bright, water-soluble, biocompatible probe capable of finding metastasized cancer cells in the blood stream and then killing these cells, according to a new research study.

The study found the spaser can be used as an optical probe and when released into the body (possibly through an injection or drinking a solution), it can find and go after circulating tumor cells (CTCs), stick to them and destroy these cells by breaking them apart to prevent cancer metastases. The spaser absorbs laser light, heats up, causes shock waves in the cell and destroys the cell membrane. The findings are published in the journal Nature Communications.

The spaser, which stands for surface plasmon amplification by stimulated emission of radiation, is a nanoparticle, about 20 nanometers in size or hundreds times smaller than human cells. It has folic acid attached to its surface, which allows selective molecular targeting of cancer cells. The folate receptor is commonly overexpressed on the surface of most human cancer cells and is weakly expressed in normal cells.

The discovery was made by researchers at Georgia State University, the University of Arkansas for Medical Sciences, the University of Arkansas at Little Rock and the Siberian Branch of the Russian Academy of Science.

“There is no other method to reliably detect and destroy CTCs,” said Dr. Mark Stockman, director of the Center for Nano-Optics and professor of physics at Georgia State. “This is the first. This biocompatible spaser can go after these cells and destroy them without killing or damaging healthy cells. Any other chemistry would damage and likely kill healthy cells. Our findings could play a pivotal role in providing a better, life-saving treatment option for cancer patients.”

Metastatic cancer occurs when cancer spreads to distant parts of the body, often to the bone, liver, lungs and brain, through a process called metastasis. Many types of cancers refer to this as stage IV cancer. Once cancer spreads, it can be difficult to control, and most metastatic cancer can’t be cured with current treatments, according to the National Institute of Health’s National Cancer Institute. One of the most dangerous ways metastasizing occurs is through the CTCs, which this study aims to detect and destroy using spasers.

The spasers used in this study measure just 22 nanometers, setting the record for the smallest nanolasers. A nanometer is one-billionth of a meter. Most results were obtained with a gold, spherical nanoparticle surrounded by a silica shell and covered with a uranine dye, which is widely used for tracing and biomedical diagnostics.

The researchers studied the spaser’s capabilities in vitro in human breast cancer cells with high folate receptor expression and endothelial cells with low folate receptor expression, as well as in mouse cells in vivo.

They found cells with spasers demonstrated high image contrasts with one or many individual “hot spots” at different laser energies above the spasing threshold. The presence of spasers was confirmed with several optical and electron microscopy techniques, which revealed an initial accumulation of individual spasers on the cell membrane followed by their entrance into the cell cytoplasm.

The study also found low toxicity of the spasers for human cells. At the same time, the spasers subjected to laser irradiation selectively killed the tumor cells without damaging the healthy ones.

Based on the study’s results, spaser-based therapeutic applications with high-contrast imaging is a promising field. The data suggest spasers have high potential as therapeutic and diagnostic agents that integrate optical diagnosis and photothermal-based cell killing, using just a few laser pulses to kill cancer cells.

Learn more: Spaser Can Detect, Kill Circulating Tumor Cells to Prevent Cancer Metastases, Study Finds

 

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Your T-shirt’s ringing: telecommunications in the spaser age

Your T-shirt?s ringing: telecommunications in the spaser age

A new version of “spaser” technology being investigated could mean that mobile phones become so small, efficient, and flexible they could be printed on clothing.

A team of researchers from Monash University’s Department of Electrical and Computer Systems Engineering (ECSE) has modelled the world’s first spaser (surface plasmon amplification by stimulated emission of radiation) to be made completely of carbon.

A spaser is effectively a nanoscale laser or nanolaser. It emits a beam of light through the vibration of free electrons, rather than the space-consuming electromagnetic wave emission process of a traditional laser.

PhD student and lead researcher Chanaka Rupasinghe said the modelled spaser design using carbon would offer many advantages.

“Other spasers designed to date are made of gold or silver nanoparticles and semiconductor quantum dots while our device would be comprised of a graphene resonator and a carbon nanotube gain element,” Chanaka said.

“The use of carbon means our spaser would be more robust and flexible, would operate at high temperatures, and be eco-friendly.

“Because of these properties, there is the possibility that in the future an extremely thin mobile phone could be printed on clothing.”

Spaser-based devices can be used as an alternative to current transistor-based devices such as microprocessors, memory, and displays to overcome current miniaturising and bandwidth limitations.

The researchers chose to develop the spaser using graphene and carbon nanotubes. They are more than a hundred times stronger than steel and can conduct heat and electricity much better than copper. They can also withstand high temperatures.

Their research showed for the first time that graphene and carbon nanotubes can interact and transfer energy to each other through light. These optical interactions are very fast and energy-efficient, and so are suitable for applications such as computer chips.

“Graphene and carbon nanotubes can be used in applications where you need strong, lightweight, conducting, and thermally stable materials due to their outstanding mechanical, electrical and optical properties. They have been tested as nanoscale antennas, electric conductors and waveguides,” Chanaka said.

Chanaka said a spaser generated high-intensity electric fields concentrated into a nanoscale space. These are much stronger than those generated by illuminating metal nanoparticles by a laser in applications such as cancer therapy.

“Scientists have already found ways to guide nanoparticles close to cancer cells. We can move graphene and carbon nanotubes following those techniques and use the high concentrate fields generated through the spasing phenomena to destroy individual cancer cells without harming the healthy cells in the body,” Chanaka said

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China Moon Rover Landing Marks a Space Program on the Rise

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China’s first moon rover rolls out from its stationary lander after touching down on the moon December 14, 2013. Credit: Xinhua/Li Xin

China cemented its reputation as the fastest rising star on the space scene this weekend by landing a rover on the moon—a challenging feat pulled off by only two nations before: the U.S. and the Soviet Union.

“This is a very big deal indeed,” says lunar scientist Paul Spudis of the Lunar and Planetary Institute in Houston. “Landing on the moon is not something easily attained—it requires precision maneuvering, tracking, computation and engineering. It is a delicate task and the Chinese success reflects a mature, evolving and capable program.”

The Chang’e 3 mission touched down on the moon Saturday (December 14) after launching December 1 on a Chinese rocket. The lander included a four-legged stationary probe and a six-wheeled robotic rover that, with mast deployed, stands about 1.5 meters tall. The spacecraft is the first man-made object to land on the moon in 37 years, and coincidentally touched down exactly 41 years after the last humans departed the lunar surface. Apollo 17 astronauts Eugene Cernan and Harrison Schmitt launched off the moon to begin their return trip on December 14, 1972, space history expert Robert Pearlman points out at collectSPACE.com.

The Chang’e 3 landing is “no small achievement,” says Roger Launius, associate director for Collections and Curatorial Affairs at the Smithsonian National Air and Space Museum in Washington, D.C. “There is a measure of pride at home and prestige abroad that accrues to the Chinese space program.” At the same time, he adds, China is replicating an achievement the U.S. and the Soviet Union mastered decades ago, and one that private teams, some of which are made up of undergraduate and graduate students, are aiming to match in the near future for the Google Lunar X PRIZE competition. “Some people who might be concerned that the Chinese are demonstrating these capabilities, and who are running around with their hair on fire—I’m not sure that’s appropriate.”

Those in a tizzy about China’s growing space prowess might include the members of Congress, led by Congressman Frank Wolf (R–Va.), who passed a law in 2011 that explicitly forbids NASA from cooperating with China on any space activities.

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