Nano cancer killers

Carbon nanotubes can allow Raman spectroscopy to be used as a technique for real-time detecting, tracking, and, with laser assistance, even killing cancer cells, according to researchers in the US.

The discovery could open up a new, battle front in the fight against cancer with the promise of a new generation of therapeutic agents beyond surgery, radiation, and conventional anticancer chemotherapy drugs.

Alex Biris of the University of Arkansas at Little Rock (UALR) is chief scientist at the Nanotechnology Center and is working with colleague in the medical sciences Vladimir Zharov, to develop the technique. They report details of their efforts in the latest issue of the Journal of Biomedical Optics.

"Until now, nobody has been able to fully understand and study in vivo and in real time how these nanoparticles travel through a living system," Biris said. "By using Raman spectroscopy, we showed that it is possible not only to monitor and detect nanomaterials moving through the circulation, but also to detect single cancer cells tagged with carbon nanotubes. In this way, we can measure their clearance rate and their biodistribution kinetics through the lymph and blood systems."

The technique the team has developed is known as in vivo Raman flow cytometry. Zharov says that it is showing promise for the detection and identification of a broad spectrum of nanoparticles with strong Raman scattering properties, such as cells, bacteria, and even viruses.

"Before any clinical application of nanoparticles, it is imperative to determine their pharmacological profiles," Zharov explains. "And this tool will provide this function as a supplement or even an alternative to the existing methods."

In the latest study, Biris, Zharov, and colleague Ekaterina Galanzha also in medical sciences injected a single human "HeLa" cancer cell containing carbon nanotube material into the tail vein of a lab rat. They were able to follow the cell through the rat's blood stream, lymphatic system, and tissues using a Raman spectrometer until it reached the rat's ear.

In a back-to-back paper, the researchers also discussed the potential of nanoparticles as tags for cancer cells in therapy, pointing out that a laser can be used to heat the nanoparticles directly and so kill the cancer cell to which they are attached.

"If we are able to target cancer cells using these nanomaterials, we can monitor where the cancer cells are specifically located, and then we can kill them," Biris explains. The hope would be that the cancer killing process would leave nothing behind but dead cancer cells and nanoparticles that would be flushed from the body with other waste products, although proof of principle on that aspect of the research remains to be carried out.

Despite the scaremongering that has surrounded the whole field of nanotechnology, the technology is so diverse and has so much potential to do good. UALR's Mary Good adds that the medical and economic ramifications of the current discovery are significant. She says that the research points to "a whole new direction for medical applications for nanoparticles."

Much follow-up work is still needed and, of course, clinical trials in humans will be necessary before the approach enters the clinic. Nevertheless, she adds, "this early work is exciting and provides long-term hope for more effective cancer treatments."

"The close location of UALR with its cutting-edge analytical chemistry and nanotechnological tools, along with UAMS and its established biological and medical infrastructures, provides unique opportunities for comprehensive pre-clinical evaluation of nanotechnological products," adds Zharov. "That allows us to accelerate nanotechnology advances from bench to bedside, providing breakthroughs in early diagnosis, prevention and effective treatment of cancers, stroke, heart attack, infections, and neurological disorders which remain the leading cause of death in the US"

"In vivo Raman flow cytometry opens a new avenue for multiparameter analysis of circulating nanoparticles with strong Raman scattering properties and their pharmokinetics in blood and lymph systems. Moreover, this technology has the potential for molecular detection and identification of circulating tumor cells, and infections labeled with CNTs," the researchers conclude.