Despite all this potential, nanomedicine must proceed cautiously. Nanomaterials can be devastatingly toxic, and while nanomedications will be well tested thanks to regulatory watchdogs, it seems nobody has a clue whether the nanomaterials already finding their way into your toothpaste will eventually kill you, except for a disturbing study showing the propensity of certain nanoparticles to cause blood clotting.

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A femtosecond laser modified to eliminate tissue damage from residual radiation represent more than just a better device for correcting poor eyesight: It is the most precise surgical tool ever developed, enabling a physician to perform surgery on an individual cell. It can be used for example to make 70 nanometer-wide incisions and drill nanoholes in cellular membranes, to destroy a diseased cell by raising the power of the laser beam, and to insert drugs or genetic material into cells using ultra-short laser pulses without destroying the cells.

It represents the start of a whole new branch of medicine: nanolaser medicine, which will deal with the diagnosis and therapy of individual cells. It is being tested at Jena University Hospital in Germany to diagnose and treat melanomas. Used as a “femtoscope,” the device renders the cell layers of the skin visible and enables diseased cells to be diagnosed by comparing samples. The diseased cell would then be radiated with increased laser power until destroyed. Subsequent biopsies and histological tests would be unnecessary.

Cancer Nanotherapy

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Researchers at Harvard Medical School and Massachusetts Institute of Technology injected engineered nanocontainers of the cancer drug Taxotere into human prostate tumors, which they then implanted into mice. The nanocontainers were made of a hydrogen and carbon polymer and the drug molecules. A substance that binds to cancer cells was added. As the polymer dissolves, the drug is slowly released.

In the carefully controlled trial, the tumor completely disappeared in the mice injected with the targeted nanoparticles containing the drug.

Clinical trials in human prostate cancer patients could begin within two years.

Nano Applied to MRI for Diapeutics

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Metal-filled nanoparticles are being developed at Virginia Commonwealth University and Virginia Tech for use with MRI to identify brain tumor cells and selectively target them for radiation therapy. The nanoparticle is called a functional metallofullerene (fMF). “In effect,” says a VCU press release, “one can look at these nanoparticles as targeted drug delivery vehicles.” It is hoped they will one day benefit patients with advanced brain tumors by enabling treatment of tumor cells that have spread beyond the visible margins of the tumor on CT and MRI scans and which are most likely to result in recurrence of the brain tumor.

The researchers have already created “a multitude of ways to attach guest molecules to the fullerene host, so the fMFs can attach to disease sites in a variety of ways, perhaps as photodynamic therapy agents.” In preliminary experiments in rats, the nanoparticles highlighted tumors more effectively than existing imaging agents. The fMF material provides improved brain tissue differentiation and a dark outline of the tumor margin, making surgical removal more precise.

In addition the team also has demonstrated that fMF is at least 40 times more effective than commercial MRI contrast agents. Another step is to make the fMFs radioactive so they can be used in treatment and make the fMFs fluoresce so the doctors can track it and watch the tumor shrink.

Nanotech Safety

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The “millions of dollars” now being spent on research into the health and environmental effects of nanoparticles — which are already out in products such as stain-resistant fabrics, tennis balls, and sunscreen — may be “nowhere near enough,” says an AP wire story. The research has already found that some of the most promising carbon nanoparticles can be toxic to animal cells. The risks to people who work with nanomaterials (and that now means factory workers, not just a handful of lab scientists), to consumers, and to the environment are just not known.

Some advocates of caution are calling for products such as sunscreen that are directly absorbed into the body to be taken off the shelf until the risks are known. Out of about US$1 billion a year spent by the US government on nanotechnology only about $6 million is spent annually on research focusing specifically on the health and environmental effects.

On the other hand, according to some scientists, the nanotechnology sector “is doing far more early research than has been done in other industries” and the risks “are being discussed openly.” “This is one of the few areas that I’ve been in that there has been a discussion at the beginning,” one researcher told the AP.

One group is maintaining an inventory of nanotech safety research as “a kind of ‘nanotech dating service’ that can not only help match up researchers with similar interests but also identify holes in the research. It shows, for example, that very little research has been focused on the gastrointestinal tract, despite the fact that toothpastes are being developed that use nanotechnology.

The executive director of an industry advocate, the NanoBusiness Alliance, (somewhat predictably) said he believes it’s premature to regulate the young industry but trust us: “If we keep our eye on the ball, we can avoid big downstream problems.”

Dangers of Nanomedicine

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Researchers from the University of Texas and Ohio University found that some carbon nanoparticles cause human blood platelets to clump together, and that the same nanoparticles stimulated blockage of the carotid artery in rats. However, the nanoparticle known variously as C60, Buckminster fullerene, and “bucky ball,” was the exception, showing no effect on human platelet aggregation and very little effect on rat thrombosis.

The team compared the impact of standard urban particulate matter, mixed carbon nanoparticles, “bucky balls,” single-wall carbon nanotubes, and multiple wall carbon nanotubes on human platelet clumping and thrombosis in rats. The mixed carbon nanoparticles had the most impact, provoking the greatest degree of platelet aggregation and the most dramatic reduction of carotid blood flow in the rats. The single-wall carbon nanotubes ranked second, the multiple wall nanotubes third, and the standard urban particulate matter fourth.

The researchers stress that “This research is not a case against nanotechnology. It’s difficult to overestimate the importance of this amazing technology’s ability to transform medicine. But it’s good to assess the risk of a new technology in advance. This is a case for moving ahead in a cautious and informed way.”