Some 40 years ago, a science fiction movie portrayed the adventures of a group of scientists who, along with a submarine, were miniaturized to submicroscopic size and then injected into the bloodstream of a dying patient so that they could perform brain surgery. As silly as FANTASTIC VOYAGE was, it dramatized some of the limitations and frustrations faced by physicians when trying to treat delicate, inaccessible tissues in the human body.

A discipline predicted by Richard Feynman as early as 1958, the emerging science of nanotechnology promises to revolutionize the practice of medicine, providing an array of submicroscopic tools that may simultaneously locate, diagnose, and treat diseases such as cancer while bypassing the hazards and discomfort of conventional therapy.

The Nanoscale

Nanotechnology deals with materials at the level of molecules and atoms — on a linear scale of from 1 to 100 nanometers (nm). By comparison, an inch is 25,400,000 nm long.

On the nanoscale, materials often display properties far different from those they typically exhibit at what we think of as normal size. A substance’s melting point, magnetic properties, or color may change — without any change in chemical composition. For instance, nanoparticles of gold absorb light, producing sufficient heat to be used as miniature thermal scalpels that can kill unwanted cells, such as cancer cells.

Nanoscale structures exist throughout nature. By copying naturally occurring nanostructures, scientists hope to be able not only to penetrate human tissues noninvasively but also to mimic or repair them.

Nanotechnology Today

Nanotechnology is already changing the way things are done in industry. Nanoscale tubes of carbon are incredibly strong and are used to make lightweight bicycles, baseball bats, and automobile parts. Nanoparticles are used increasingly in a broad array of products, including antibacterial wound dressings, sunscreens, and scratch- and glare-resistant eyeglass coatings.

The Nanomedicine Initiative

Introduced by the National Institutes of Health in late 2003, the Nanomedicine Initiative established a national network of eight Nanomedicine Development Centers, staffed by multidisciplinary teams of biologists, physicians, mathematicians, engineers, and computer scientists.

Initial research has focused on the physical properties of intracellular structures with the goal of discovering how biology’s molecular machines are built. The ultimate goal of this mission is to develop nanotechnology with which scientists can create synthetic biological devices capable of treating and preventing disease, restoring function after traumatic injury, and preserving and improving human health. Miniaturization of medical tools will bring greater accuracy, control, and versatility to health care while increasing speed and cost-effectiveness of treatment.

Nanomedicine research conducted by both the NIH and organizations worldwide is investigating hundreds of potential applications for this new technology. While some products will be introduced within the next few years, others will take much longer — even decades — to be fully developed. The following are just a few areas of study.

• Immunoisolation. The immune response — the body’s automatic effort to destroy foreign tissue — not only complicates organ transplantation, it has hindered efforts to introduce islet cells capable of restoring normal glucose control in patients with diabetes. Using immunosuppressive drugs to preserve these foreign cells increases the risk of serious infection. Technology already exists to enclose islet cells in silicone capsules covered with tiny pores just 20 nm in diameter — large enough to allow the passage of small molecules such as oxygen, glucose, and insulin but small enough to prevent immune system molecules from attacking the islet cells. This technology may also prove effective in allowing neurons to be implanted in the brain as part of treatment for Parkinson’s and Alzheimer’s diseases.
• Fullerene-based drugs. Soluble derivatives of fullerenes (a class of superconductive carbon molecules) have little toxicity in humans, even at high dosages. Drugs formed with these molecules are already in clinical trials and are expected to provide treatments for HIV and other viruses, bacterial infections including E. coli and streptococcus, certain cancers, amyotrophic lateral sclerosis (Lou Gehrig’s disease), and Parkinson’s disease.
• Starburst dendrimers. These tree-shaped synthetic molecules may become the basis for multitasking smart therapeutic nanodevices that could recognize diseased cells, diagnose the specific disease, treat the disease with drugs, and even report the disease location and treatment result to the physician. The same technology could be used against virus-infected cells and parasites.
• Biorobots. These synthetic microbes could be used to manufacture useful vitamins, hormones, enzymes, or cytokines in patients who produce insufficient amounts. They might also be used to absorb poisons or toxins and metabolize them into harmless substances.
• Respirocytes. These artificial mechanical red blood cells would be able to manufacture 236 times more oxygen than the same volume of natural red blood cells in patients needing transfusion as well as those with anemia and lung disorders, during surgery, and in trauma patients.
• Microbivores. These artificial white blood cells could fully eliminate dangerous infections within minutes or hours instead of days or weeks.
• Chromosome replacement therapy. Nanorobots may be able to surgically replace chromosomes in diseased cells. The new chromosomes would be manufactured to order, using the patient’s own genome as a blueprint. The same technology could be used to replace inherited defective genes, permanently curing a genetic disease.