Killer - Americaâ€™s war on AIDS continues. The Centers for Disease
Control and Prevention (CDC) estimates that the number of Americans who
have died from AIDS has reached more than 430,000 and as many as 900,000
Americans are living with HIV infection. One of the reasons AIDS affects
so many people is that intravenous drug use is on the rise, especially
among young people. But researchers are now looking at heat as a way to
kill the killer virus. (10/19/00)
Detector - The post office is in the final stages of a detection
system that would alert them to the presence of biological agents like
anthrax in mail. But nearly a year after the 9/11 attacks, we still have
a long way to go for that perfect detector. (8/30/02)
Elsewhere on the web
American animation on how nano will change medicine
article on Nanosphere
Doctors cannot detect and diagnose an infectious disease very quickly or easily
these days: the necessary means donâ€™t exist.
But as this ScienCentral news video reports, nanotechnology promises to deliver
the right tools: minute gold particles that are simple to use, yet powerful
enough to detect biological threats anywhere.
Sick Enough to Change Color
Nanotechnologists expect to transform medicine, and along with it, our well-being.
At Northwestern University, chemist Chad
A. Mirkin noticed that right now, it is often impossible for a doctor to
detect, diagnose, and treat a patient with an infectious disease during a single
office visit. Currently, both doctor and patient must wait several days before
expensive, complicated, slow tests can tell them whatâ€™s wrong. In cases
of serious illnesses, such as the anthrax
attacks of 2001, patients may be dead by the time medicine knows how to
Mirkin decided to use nanotechnology to develop more powerful technology.
By working so small, he could detect many more diseases, much more quickly.
His new approach would be inexpensive, yet simple enough for a nurse or physicianâ€™s
assistant to use, either at a doctorâ€™s office, on a battlefield, at a
reservoir, or any other place that may have been contaminated. At the same time,
Mirkinâ€™s system is very sensitive - able to detect even very small
traces of infection - and very powerful - capable of distinguishing
many different kinds of diseases accurately, and diagnosing them simultaneously.
Mirkin starts with gold particles, each only a few nanometers in diameter.
To grasp the nanoscale, Mirkin suggests starting with a dime, which is about
a millimeter thick. If the dime were sliced into a thousand pieces, each piece
would be one micrometer thick, or one thousand nanometers. If that piece were
sliced into another thousand pieces, it would then be one nanometer. Each of
the gold particles that Mirkin uses is about 13 nanometers wide.
At the nanoscale, all the properties of any material change, including its
color. Gold becomes a strong red: “In the Middle Ages,” Mirkin says,
“people used gold particles as dyes in stained
glass windows.” By varying the size or shape of his particles -
for example, using triangles instead of spheres, he can have a vast range of
colors available - colors that can translate into codes. If he uses silver,
he can create codes in the blue or green range of shades.
Collaborating with experts in materials and genetics, Mirkinâ€™s research
group attached miniscule bits of genetic material to the gold particles. “Anything
living has a genetic marker,” Mirkin explains, “a fragment of DNA
that is unique to it.” The DNA-carrying
gold particles recognize the DNA of disease agents. Once the particles are
released in a blood, urine, or saliva sample taken from a patient, the genetic
material latches on to an infectious agent. After minimal processing, the particles
give off color signals that can be read on a monitor. The particles can work
like a litmus test for a single agent, giving off a blue signal for positive
and red for negative. Or a color code can signal whether many disease agents
are present at once.
Mirkin points out that rapid diagnosis is important in any case of infectious
illness - and absolutely vital to combat bioterrorism or biowarfare. He
is working with Nanosphere,
a company that plans to market a toaster-sized version of his new disease detection
system that could be part of a mobile defense unit. Eventually, he foresees
units the size of todayâ€™s Palm Pilots which could remain in doctorsâ€™
offices or travel into battle in medicsâ€™ backpacks.
His research was supported by the Defense
Advanced Research Projects Agency, the Air
Force Office of Scientific Research and the National