Scientific News  Health care Oncology PROTEIN-LIKE MOLECULES COULD FORM MEDICAL DEVICES, ELECTRONICS
PROTEIN-LIKE
MOLECULES COULD FORM MEDICAL DEVICES, ELECTRONICS
 A new kind of artificial protein-like molecule
created at Ohio State
University could one day lead to new drugs, new medical treatments -- and
even faster computer chips.
"Proteins come in so many shapes and sizes
that they are able to perform a wide variety of functions," said Jonathan
Parquette, assistant professor of chemistry at Ohio
State. "We wanted to mimic that versatile structure in a synthetic form."
Parquette and his students built the molecules,
called dendrimers, from tiny, spaghetti-like plastic filaments. Researchers have
long tried to mimic the shape of proteins using dendrimers, but the Ohio
State group is the first to coax the soft, tangled filaments to maintain a
shape that suits needed applications.
The molecule is shaped like a sphere, supported
by branching beams of polymer inside, with hollow portions that could
theoretically hold drugs or other chemicals. Parquette described his work
September 23 at the BioMEMS and Biomedical Nanotechnology World 2001 meeting in
Columbus, Ohio.
BioMEMS, or biomedical microelectromechanical
systems, are microscopic medical devices under development around the world. The
tiny devices can be as small as a few millionths of a meter -- much smaller than
the width of a human hair.
Parquette's synthetic protein molecule belongs to
the realm of nanotechnology, which concerns devices even smaller than bioMEMS.
The molecule is about the same size as a small protein or a short sequence of
DNA -- a few tens of atoms across.
The chemists are working toward developing the
molecule into a larger, more complex structure.
Ultimately, synthetic proteins could act as
devices to deliver medicine to tumors or other sites of disease in the body.
They could also act as catalysts for chemical reactions that produce drugs, or
form computer chips for light-responsive molecular electronics.
For these molecules to perform such tasks, the
outer shell would have to open and close on cue, Parquette explained. A molecule
could locate a tumor, for instance, and unravel its structure to release
cancer-fighting medicine from within.
"Along the outside of the molecule, the
atoms fasten together like a zipper," Parquette explained. "Getting
them to zip up is half the puzzle. Getting them to unzip on demand is the other
half."
With chemicals, the researchers caused the
normally long, stringy dendrimers to fold into a protein-like shape. Then they
added other chemicals that bound themselves to select sites along the dendrimers,
effectively zipping together layers of folds and stiffening the structure
overall.
Currently, Parquette and his colleagues are
investigating whether light could be used as a stimulus to make the dendrimers
unfold. If so, the protein-like molecules could form the basis for extremely
tiny, very fast computer chips.
Whereas semiconductor computer chips carry a
digital signal of "one" or "zero" based on the presence of
an electron, molecular computer chips stimulated by light from fiber optics
could carry a signal based on whether individual molecules were "zipped"
or "unzipped."
For Parquette, this work has helped to explain
how nature builds its own micrometer- and nanometer-size structures.
"On the nanoscale, it seems that atoms have
a way of cooperating together to assume certain structures for specific
functions. If we can learn to harness that cooperativity, we may be able to form
better synthetic molecules," Parquette said.
"As soon as you think you're pretty smart
about something, it turns out nature has thought of it first," he said with
a smile.
###
This work was supported by Parquette's Faculty
Early Career Development (CAREER) award from the National Science Foundation.
Contact:
Source of the given news and the copyrights
belong to a Ohio
State University
Publishing date: October 3, 2001
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