Nanotechnology and Prostate Cancer
To the incredibly tiny gold particles doctors send to search a blood sample for signs of illness, human cells would seem as big as mountains. But the particles' mission is to hunt down something more their size: prostate specific antigen, or PSA, a signal that prostate cancer may be on its way to returning, long before it does.
Welcome to the new frontier of nanotechnology, where scientists are learning how to make super-small devices, as small as genes and proteins, to diagnose diseases that remain unseen with present equipment and to provide treatments tailored to affect individual cells.
"The particles go into a blood sample, and if there are as few as 10 molecules of PSA present, they will find them," said Chad Mirkin, director of Northwestern University's Institute for Nanotechnology. "The current test would need 10 million molecules of PSA to record a positive reading."
Capitalizing on the promise of the field, the National Cancer Institute announced Sept. 13 a $144.3 million program to establish the National Nanotechnology Standardization Laboratory and to set up at least five nanotechnology-research centers across the nation. Experts hope the field will produce new ways for detecting, diagnosing, treating and preventing cancer in the next five to 15 years.
Many nanotechnology projects are under way at research institutions across the nation, with Northwestern playing a major role in the field. The technology involves the construction of tiny tools that can be designed to carry almost any type of gene or protein and designed to target specific locations in the body. The devices are made of a variety inorganic materials and are engineered into optimal shapes, including capsules, tubes and flattened pieces with many prongs.
The precision with which the particles home in on cancer cells also enables researchers at Northwestern's Medical School to work on developing drugs to ride along with the particles and destroy malignant prostate cells where they live. "Nanotechnology can completely change the way we think about diagnosing many forms of cancer," Mirkin said. "We can now begin to look at markers that the rest of the world can't even touch with the old technology. It's opening up many avenues that could lead to major advances in terms of treating cancer." Science is learning more about the human body on a smaller and smaller scale. The genetics revolution, for example, is revealing genes that cause disease or predispose people to certain ailments, and biologists are discovering protein molecules that are crucial for maintaining health as well as molecules that drive disease processes.
Because nanotechnology is such a recent science, doctors have not had tools small enough to work in this ultra-small universe. Everything physicians use now is huge by comparison. Drugs work at the cellular level because of their natural ability to dissolve in liquids. But the drawback is that medications often affect healthy cells as well as diseased ones, creating the risk of adverse effects.
For the last decade, scientists have been trying with limited success to develop so-called "smart drugs" that could be directed to specific tissue. Researchers say the nanotechnology developed in the last five years has a much better chance of achieving the same goal by engineering metals and other inorganic substances to target and deliver treatment. In developing tools to work on this scale, scientists were surprised to find that material shrunk to less than 100 nanometers takes on new properties. Gold particles of various sizes, for instance, will emit different colors when exposed to ultraviolet light, a feature that can be used to identify them. The particles are coated with bits of DNA or antibodies that enable them to hook up only with a particular target. "By making groups of these particles that can recognize proteins or DNA markers associated with disease, you can design them to detect just about anything, ranging from Alzheimer's disease to different forms of cancer, HIV, genetic diseases, all sorts of sexually transmitted disease and genetic predispositions to disease," Mirkin said.
A top goal of researchers is the development of cancer nanobombs, tiny particles that seek and destroy cancer cells. Jim Shaw
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