New Brunswick / Piscataway, New
Jersey
January 17, 2006Tiny
chemical cages created by researchers at
Rutgers, The State University
of New Jersey, show potential for delivering drugs to organs
or tissues where they’re needed without causing harm elsewhere.
Illustration of a nanocontainer molecule. |
These cage-like molecules, called
nanocontainers or nanoscale capsules because they measure a mere
3.2 nanometers (billionths of a meter) wide, also could make
pesticides less hazardous to handle, filter toxic substances out
of wastewater and regulate the pace of reactions in chemical
production.
“While the concept of chemical
cages is not new, we’ve created new components and advanced the
assembly process to increase the chance that they’ll become
practical,” said Ralf Warmuth, associate professor of chemistry
and chemical biology at Rutgers and lead researcher. “We’ve
shown a way to securely link molecules together in a cage using
an efficient, one-step process.”
In an article slated for an
upcoming issue of the chemistry journal Angewandte Chemie
International Edition, now available
on the journal’s Web site,
Warmuth and colleagues describe how they’ve used common organic
chemicals and straightforward techniques to create
nanocontainers. These octahedral (eight-sided) capsules, with
their cavity volume of almost two cubic nanometers, could
enclose one or more molecules of a medicine, pesticide or
intermediate in a chemical manufacturing process that, if left
uncaged, might prematurely decay or interact with other
substances in passing.
A stick representation of a nanocontainer molecule |
Previous techniques for
assembling molecular cages involved tradeoffs. With one
approach, the synthesis technique was straightforward, but the
pieces of the molecular cages were not bound as tightly to each
other. Another approach resulted in tighter bonds, but the
process required several carefully orchestrated steps. The
Rutgers advance is a one-step process that creates tight
chemical bonds, surpassing earlier approaches in simplicity and
efficiency.
The Rutgers process involves
combining six larger bowl-shaped molecules with 12 smaller
linear molecules, or bridges, that link the bowls together,
insides facing each other. Atoms at four sites along each bowl’s
rim bond to atoms on the ends of the bridges. The atomic
structure and properties of these molecules ensure that they
naturally assemble themselves into capsules and do so with high
yield when combined in proper proportions. Early research
suggests that the connections between the bridges and bowls can
be broken and reattached under controlled conditions to
introduce “payload” molecules – such as a drug or pesticide –
into the cage and extract them when needed.
The Rutgers team consisted of
Warmuth, chemistry graduate students Xuejun Liu and Yong Liu,
and undergraduate student Gina Li. The work was funded by grants
from the National Science Foundation.
Registered users can view the
full text of the journal article at:
www3.interscience.wiley.com/cgi-bin/fulltext/112223539/PDFSTART
Images courtesy of Ralf Warmuth.
Permission is granted to reproduce the images in connection with
news coverage of this story. All other rights are reserved.
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