Nanotechnology is the molecular manufacture of very small things. Derived from the Greek word "nano," meaning dwarf, it involves components that range from approximately five to 500 nanometers in diameter (one nanometer is one millionth of a millimeter).
Nanocomponents form the base for delivery systems that will, it is hoped, ferry therapeutics or diagnostic agents to specific sites in the body, allowing for highly targeted treatments that should minimize side effects. Drugs that would normally exhibit toxicity when delivered in large doses may prove to be ideal therapeutics when delivered by nanotechnology methods.
Discovery and Early Research
The birth of nanotechnology is usually attributed to physicist Richard Feynman's 1959 talk, "There's Plenty of Room at the Bottom," although he actually did not use the term in the talk delivered to the American Physical Society. During his talk, Feynman suggested a 1/25,000 reduction in type size that would permit the entire Encyclopedia Britannica to be contained on the head of a pin. He offered $1,000 to anyone who could develop a method to do so and, in 1985, a Stanford graduate student claimed the prize by reducing the first paragraph of A Tale of Two Cities.
Feynman also described his vision of mechanical robots, each programmed to build a set of tools that could construct a smaller robot to build even smaller tools, eventually culminating in a billion tiny factories. This idea was picked up and expanded on by one of Feynman's students, K. Eric Drexler, whose 1986 book, Engines of Creation: The Coming Age of Nanotechnology, brought the field to wide popular attention. The term nanotechnology itself had been coined in 1974 by a Tokyo Science University Professor, Norio Taniguchi, and unwittingly appropriated by Dexler.
The first scientific conference on nanotechnology in biology, "Biological Approaches and Novel Applications for Molecular Nanotechnology" was held in 1996, in San Diego, and sponsored by International Business Communications. In 1999, Robert Freitas, Jr., a senior research fellow at the Institute for Molecular Manufacturing in Palo Alto, published the first book in his series, Nanomedicine, describing how molecular machine systems could be engineered to address medical problems.
Nanotechnology and Cancer
Nanotechnology devices are being developed for several cancer applications. Many groups are attempting to target tumor angiogenesis, the growth and recruitment of blood vessels that characterize and are essential to the growth of many solid and hematological cancers. Others are focusing on homing nanoparticles to the lymphatic system - recent results demonstrate that many breast cancers, for example, utilize lymphatic vessels unique to the tumor. If these vessels can be targeted and destroyed by nanotechnology, tumor growth should be compromised.
In the diagnostic realm, nanoparticles have been used to enhance the efficacy of magnetic resonance imaging to detect the spread of cancer. In one study, lymphotropic iron oxide nanoparticles were demonstrated to act as effective contrast agents and allowed the detection of small nodal metastases in men with prostate cancer that would otherwise have been overlooked. Such imaging with nanoparticles might also help eliminate invasive biopsy procedures as the only means to monitor a cancer's spread. Nanoparticle contrast agents for ultrasound have also been developed, which may enhance the sensitive detection of vascular and cardiac thrombi, as well as solid tumors of the colon, liver and breast, in a noninvasive manner.
In 2008, researchers presented data that suggested nanoparticle delivery of a p21, a known tumor suppressor protein, by the Antennapedia protein could pierce the outer layer of a cancer cell and successfully reduce malignant tumors. Although the research was conducted in mice, researchers speculated that it could be a promising therapeutic application for many carcinomas.
Also in 2008, researchers found that green tea, a known cancer preventive agent, was more effective when delivered on a synthetic nanoparticle. Researchers tested the effect on prostate cancer cells and found a significant response that persisted for 48 to 72 hours.