Cork for nano tubes gives drug-delivery potential
15 May 2006
Scientists at the University of Florida have found a way to
“cork” nano tubes. The goal is a better way to deliver drugs, for
example, for cancer treatment. Scientists want to find a way to fill the
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.
|Rows of tiny nano test tubes rest on a mesh in
this electron microscope photo, colorized for added clarity. Source:
University of Florida
“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.
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 used to make biodegradable sutures.
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 in 2004.
cork the 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.
A small mesh that holds millions of amino-modified nanotubes, all precisely
lined up in a grid pattern, are immersed into a solution imbued with
millions of the corks. The chemical attraction pulls the corks into the
mouths of the tubes.
The 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.
There is still one problem to solve to use the tubes for drug delivery,
however. The Florida scientists still have to find a way to unlock the amino
chemical group from the aldehyde chemical group to release the corks and the
drugs at the desired site.