Nanoshells Simultaneously Detect And Destroy Cancerous Cells

Researchers at Rice University in Texas have developed a new approach to fighting cancer, based on nanoscale particles that can both detect and destroy cancerous cells. The report appears in the April 13 issue of the American Chemical Society's journal Nano Letters.

Current molecular imaging approaches only detect the cancer but don't offer a method of treatment, according to the study's lead authors, Rebekah Drezek, Ph.D., and Jennifer West, Ph.D., both professors in the Department of Bioengineering at Rice.

"You can look for a molecular marker that may indicate a significant clinical problem, but you can't do anything about it (just through imaging)," says Drezek.

"We don't want to simply find the cancerous cells. We would like to locate the cells, be able to make a rational choice about whether they need to be destroyed and, if so, proceed immediately to treatment."

To this end, Drezek and West collaborated to develop a new imaging and treatment method based on metal "nanoshells" - tiny spheres of silica coated with a thin layer of gold.

Nanoshells were invented by electrical engineer Naomi Halas, Ph.D., also of Rice University.

Because these spheres are constructed on the nanometer scale (one billionth of a meter, the range where molecular interactions take place), they exhibit unique size-dependent behavior, such as tunable optical properties.

This allows researchers to design particles that scatter and absorb light at particular wavelengths.

The scattering of light provides the optical signal used to detect the cancer cells, which then "light up" when they come into contact with the nanoshells.

In this study, the researchers designed the nanoshells to look for breast cancer biomarkers on the surface of the cancer cells.

The technique can be readily extended to target other types of cancer or disease processes that have known surface markers.

The additional ability of the particles to absorb light is used to generate heat, which then destroys the cancer cells.

"Nanoshells are very unique in that we can engineer the particles so that both the optical scattering and absorption peaks occur in the near-infrared (NIR) spectral region where light penetration through tissue is highest," Drezek says.

The NIR absorption also makes destruction of the targeted cells less invasive for patients because it uses a light source from outside the body that passes harmlessly through normal tissue and only heats the tissue containing nanoshells.

The new approach has some significant advantages over other alternatives that are under development, according to Drezek.

For instance, optical imaging is much faster and less expensive than other medical imaging techniques. Gold nanoparticles are also more biocompatible than other types of optically active nanoparticles, such as quantum dots.

Gold is a chemically inert material that is well-known for its biocompatibility, which is why it has found use in a variety of medical applications in the past.

"There is a prior history of the use of gold inside the body that makes the safety issues somewhat easier to address," Drezek says.

Of course, any new technology requires extensive safety assessment before coming to market, but initial results from nanoshells testing are promising.

Nanoshells developed for therapeutic applications have already been evaluated by Nanospectra Biosciences, the Houston-based company that is commercializing the technology, with no ill effects found, according to Drezek.

Drezek and West have successfully tested the separate imaging and therapy aspects of the nanoshells in animals and are now evaluating the combined imaging/therapy nanoshells in a mouse tumor model, which they expect to complete within the next six months.

About 1/20th the size of a red blood cell, nanoshells (illustrated above) are about the size of a virus. They are ball-shaped and consist of a core of non-conducting glass that is covered by a metallic shell, typically either gold or silver. Discovered by Halas at Rice in the 1990s, nanoshells are already being developed for applications including cancer diagnosis, cancer therapy, diagnosis and testing for proteins associated with Alzheimer's disease, drug delivery and rapid whole-blood immunoassay.

Interesting. I just read another article that said that scientists are genetically altering viruses to go after cancer cells. Apparently it has worked in tests on mice but is several years away from human testing. One group of researchers genetically altered the measles virus and another group altered the HIV virus. The modified virus attaches to and kills only cancer cells. The virus does not affect the body in any other way. Looks like we may be on the road to curing cancer either way.

Would a socialized medicine system allow a treatment which let people live for, just say, 150 ACTIVE years?

Or would ted kennedy demand the SS age be raised to 155?

This is merely an adaptation of the work done by Dr Royal Rife back in the '20s. His system used resonant frequency vibration to destroy the cancer cells (leaving the healthy cells intact), this system uses near IR to induce the shaking in those cells.

Gold is biocompatible at that size, but I wonder about the substrate and any reactions it may have with the blood system. (Bead blasting of arterial walls for instance.)

Seems as though the old method offers proven results with no invasive effects, in a machine you can build yourself for about $1500.

tiny spheres of silica coated with a thin layer of gold.

Sounds familiar...

8 posted on 04/14/2005 11:59:28 PM PDT by Lexinom (You can easily judge the character of a man by how he treats those who can do nothing for him.)

This looks promising. The idea is right: traditional chemo drugs kill anything that grows fast, hence the hair loss (quickly-changing folicle cells) and nausea (rapid turnover in GI tract lining).

I wonder if nanoshell technology could be combined with other technology such as positron emission tomography to help its accuracy. If nontoxic equivalent to stains like Cytokeratin 7 could be applied systemically such that they would bind to tumor cells in preference to normal cells, that, too, would be offer a powerful targeting mechanism.

9 posted on 04/15/2005 12:15:08 AM PDT by Lexinom (You can easily judge the character of a man by how he treats those who can do nothing for him.)

10 posted on 04/15/2005 12:58:09 AM PDT by AmericanArchConservative (Armour on, Lances high, Swords out, Bows drawn, Shields front ... Eagles UP!)

Yes, now if we all can manage to just LIVE long enough for these wonderful medical discoveries to reach the common man, we'll live forever... Really though, this is but another example of surface effects at the molecular scale/quantum scale that illustrate how alien technology is rapidly coming within our grasp...if we have the MATURITY not to destroy ourselves with it. The AG breakthrough was discovered along these same surface effects approach.

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