Fla. — Now all they need is a really, really small
Lilliputian chemists, scientists have found a way
to “cork” infinitesimally
small nano test tubes. The goal is a better way
to deliver drugs, for example, for cancer treatment.
Scientists want to fill the teeny tubes with drugs
and inject them into the body, where they will
seek diseased or cancerous cells, uncork and spill
their therapeutic contents in the right place.
“After making the nano test tubes, we saw the potential
for them to be used for drug delivery vehicles, but
because they are open at one end it would be like
trying to ship wine in a bottle without a cork,” said University
of Florida chemistry professor Charles
Martin . “You have to cork it, which is what
we have accomplished.”
Martin is one of six University of Florida chemistry
faculty members and graduate students who co-authored
a paper about the research that appeared last month
in the Journal
of the American Chemical Society .
While chemotherapy works against many cancers, it
can cause severe side effects such as nausea, temporary
hair loss and blood disease. To make the chemo hit
only the cancerous cells, Martin and scientists elsewhere
have spent recent years experimenting with drug-carrying
nanotubes or nanoparticles.
from nanotechnology, the fast-growing science of
making objects or devices that approach molecular
dimensions. One nanometer equals one-billionth
of a meter.
The approach makes sense for attacking diseased
cells while bypassing healthy ones, but it also poses
challenges. For one thing, the nanotubes must recognize
their target, a problem scientists are attacking
by tweaking their chemistry to make it respond to
the unique chemistry of cancer cells. The tubes also
must be biologically benign. Martin says a method
for making nanotubes he pioneered, template synthesis,
allows manufacturers to use biodegradable material,
such as the polylactides that compose biodegradable
Additionally, the tubes also had to be closed at
one end to form the classic test tube shape, a problem
Martin and his group solved in research published
To “cork” the
test tubes in the latest research, the researchers
applied an amino chemical group to the mouth of
the tubes and an aldehyde chemical group to the
corks. The two groups are complementary, so they
bond with one another.
of nanotubes could fit on a postage stamp. So,
said Martin, “we don't put individual caps in
each nanotube the way corking machines do for bottles.”
the scientists immerse a small mesh that holds
millions of amino-modified nanotubes, all precisely
lined up in a grid pattern, into a solution imbued
with millions of the corks. Brownian motion — what
happens when minute particles immersed in a fluid
move about randomly — takes care of the rest. The
corks simply float around, then slip into the mouths
of the tubes as they encounter them.
diameter of the tubes is about 80 nanometers, or
80-billionths of a meter. Even though they are
tiny, each tube can hold about 5 million drug molecules. “Each
tube packs a real punch in terms of the number of
drug molecules it can deliver,” Martin said.
Bok Lee , an assistant professor of chemistry
and biochemistry at the University
of Maryland , works on similar research. He
said scientists have proposed capping the tubes
using chemical interactions between the drugs and
the tubes. But that might not work because the
tube could leak before it reaches its target.
“I strongly agree that Professor Martin's proposed
strategy will be one of the ideal solutions for the
problem of controlling drug uptake and release,” he
said in an e-mail.
The UF scientists aren't there yet. There's no easy
way to unlock the amino chemical group from the aldehyde
chemical group. So while Martin says there are some
promising possibilities, he and his colleagues have
their next job cut out for them: figuring out how
to uncork the tubes.
Writer Aaron Hoover, firstname.lastname@example.org ,
Source Charles Martin, email@example.com ,