By Cat Holmes
University of Georgia
Diabetics who must frequently monitor their blood sugar levels
can take heart. University of Georgia research engineers are
developing tiny sensors that could eliminate the need for all
those finger sticks.
“There are lots of problems with the current technology (for
measuring blood sugar),” said Guigen Zhang, one of three main
researchers on the UGA project. “It’s not particularly accurate
or stable, and it’s especially hard for children.”
Zhang and his colleagues, bioengineer William Kisaalita and
physicist Yiping Zhao, are working to create the first
generation of nanoscale biosensors, funded by a four-year, $1
million National Science Foundation grant.
Nanotechnology is the study and design of nanoscale systems —
literally, measured in nanometers, or billionths of a meter.
“The idea is to create devices that can be imbedded in the body
to monitor conditions — in this case, glucose for diabetes,”
said Zhang, a bioengineer in the UGA department of biological
and agricultural engineering.
“But the application potential for this nanotechnology is very
broad,” he said. “We can imagine adapting it for food safety,
to monitor the environment (and for) biodefense.”
Nanoscale structures
So, how does one go about making anything, much less a
functional structure, on such a small scale?
That task, for this project, falls principally to Zhao, who
uses a technology called glancing angle deposition (GLAD) to
create nanostructures. With GLAD, substances like metal or
silicon are heated until they vaporize and are then manipulated
to create structures.
“The unique part is that these are well-controlled structures,
not random,” Zhang said. “The GLAD technology is not new. But
using it to make nanostructured devices is relatively new, and
using it as we are is very, very new.”
Nanoscale problems
However, before the scientists start work on the structures,
they must first address two basic problems that occur with any
biosensor, large or small.
One, biofouling, occurs when the sensor mechanism gets blocked.
Just as dust particles can interfere with satellite reception,
molecules, often proteins, can mar the surface of a nanoscale
biosensor.
When this happens, “it blocks the reaction of the sensor,”
Zhang said, “and interferes with the sensor’s ability to track
signals.”
The other critical issue is long-term calibration. Sensor
devices must be calibrated regularly, in the same way bathroom
scales must regularly be adjusted back to zero.
Solving the problem of how to recalibrate minute, implanted
nanodevices will have broad applications for the whole of
nanotechnology, particularly nanobiotechnology, Zhang said.
Nanobiosensors will provide more accurate readings, he said,
because many tiny sensors are better than one larger one and
increase the sensitivity of the sensing.
Nanotechnology futures
Almost 17 million people in the United States have diabetes,
according to the American Diabetes Association. Many must
monitor their glucose level several times each day. And each
time they must draw blood from a finger, hand or arm.
Helen Brittain, 54, has been sticking her finger five or six
times a day for almost 20 years.
“You have to get used to it, but I’d rather not have to do it,”
she said. “I spend a lot of energy keeping myself balanced.”
Creating more accurate and convenient measuring systems will
have a “huge social impact,” Zhang said.
“We’re excited at many levels by this project,” Zhang said. “By
harnessing interdisciplinary expertise through the UGA Faculty
of Engineering, we’ve not only brought federal dollars to
Georgia but we have the opportunity to play a significant role
in very cutting-edge technology.”
(Cat Holmes is a news editor for the University of Georgia
College of Agricultural and Environmental Sciences.)
