This image
illustrates pumping in two directions at once with an enzyme patch. A patch of
enzymes
immobilized on a
surface acts as a fluid pump. The fluid, and the small particles (green
spheres)
carried by the
fluid, can simultaneously be pumped away from the patch (blue) in some parts of
the
chamber and toward
the patch (red) in other locations. This behavior changes over time and is due
to the changes in
fluid density that the reaction produces. Image: University of Pittsburgh
(February 25, 2016) A
new way to use the chemical reactions of certain enzymes to trigger
self-powered mechanical movement has been developed by a team of researchers at
Penn State University and the University of Pittsburgh. A paper describing the
team's research, titled "Convective flow reversal in self-powered enzyme
micropumps," is published this week in the journal Proceedings of the
National Academy of Sciences.
"These pumps provide precise control over flow rate
without the aid of an external power source and are capable of turning on in
response to specific chemicals in solution," said Ayusman Sen,
Distinguished Professor of Chemistry at Penn State. "They also can remain
viable and capable of turning on even after prolonged storage." Sen and
Penn State graduate student Isamar Ortiz did the research team's experiments,
which reveal that "simple reactions triggered by enzymes can be used to
combine sensing and fluid pumping into single non-mechanical, self-powered,
nano/microscale pumps that precisely control flow rate, and that turn on in
response to specific stimuli," said Sen, who also made the initial
discovery of enzyme pumps.
Potential uses of the self-powered enzyme micropumps include
detecting substances, moving particles to build small structures, and
delivering medications. "One potential use is the release of insulin to a
diabetes patient from a reservoir at a rate proportional to the concentration
of glucose in the person's blood," Sen said. "Another example is an enzyme
pump that is triggered by nerve toxins to release an antidote agent to
decontaminate and treat an exposed person. Also, because enzyme pumps can pump
particles suspended in a fluid, it also should be possible to use them to
assemble or disassemble small structures in specific locations by directional
pumping."