A University of Arkansas for Medical Sciences (UAMS) research team led by Vladimir Zharov, Ph.D., D.Sc., has demonstrated the ability to kill single cancer cells using the world's smallest laser.

At 22 nanometers in diameter, the laser -; known as a spaser -; is capable of detecting and killing single cancer cells by generating super-bright light directly in the cells and transforming the light into heat, nanobubbles and sound waves. One nanometer is equal to one billionth of a meter.

The team's findings titled "Spaser as a Biological Probe" were published in the June 8 issue of Nature Communications, a prestigious scientific journal published by Nature Publishing Group.

Zharov is director of the Arkansas Nanomedicine Center at UAMS and a professor in the UAMS College of Medicine Department of Otolarynology-Head and Neck Surgery.

"The use of lasers has revolutionized disease diagnosis and treatment. However, the large size of lasers has prevented their use in many medical applications at the cellular level," said Zharov, who in 2003 pioneered the use of laser-induced vapor nanobubbles around overheated nanoparticle clusters to kill single tumor cells without harming neighboring normal cells.

"Researchers under the direction of Dr. Vladimir Zharov have used this technology in a novel and exciting way to detect and destroy circulating cancer cells with new precision. These cellular probes can likewise be bonded with compounds, such as folic acid, for molecular targeting of individual cancer cells in a therapeutic fashion without interaction with normal cells. This exciting research may eventually allow detection and treatment of cancers cells before they have the chance to metastasize," said John Dornhoffer, M.D., chairman of the Department of Otolaryngology – Head and Neck Surgery in the UAMS College of Medicine.

The extremely small size of the spaser -; which stands for Surface Plasmon Amplification by Stimulated Emission of Radiation -; overcomes these limitations and has shown the potential both to diagnose and treat cancer at the cellular level. Moreover, Zharov's team has discovered a new principle of pulse laser using transient vapor nanobubbles around the nanobubble spaser as part of a laser schematic leading to giant generation of spaser light.

The research team has demonstrated a laser regimen with an emission intensity and spectral width more than 100 times brighter and 30-fold narrower than for quantum dots.

Quantum dots are one of the best tiny, man-made probes that display unique optical properties. While quantum dots used as diagnostic nanoprobes are important to understanding cell biology, toxicity, light degradation, and other concerns limit their application in humans. Because of the spaser's super-brightness and that its components have low toxicity, it shows more promise for potential use in people.

"According to our data, spasers are small enough so as not to adversely influence cell functions, specific enough to target desired cells, bright enough to be detectable in complex biological backgrounds, and plasmonically active enough to generate the desired photomechanical therapeutic effect that can kill tumor cells, such as triple negative breast cancer cells that are resistant to conventional chemotherapy," Zharov said.