7.12 Using mitochondria to power sensors for explosives
By Yun Xie | Published:
October 27, 2008 - 01:04PM CT
We learned in introductory
biology classes that mitochondria are the power plants of cells. A simple
concept like this can be easily taken for granted, but chemists like Saint
Louis University professor Shelley Minteer see creative applications. She proposed
that mitochondria can be incorporated into a biofuel cell to make devices such
as self-powered sensors for explosives.
Depictions of mitochondria.
Minteer and her colleagues
immobilized intact mitochondria on carbon anodes. Cellular mitochondria are
capable of oxidizing "fuels" such as pyruvate to produce energy, so
the mitochondria on the anode should catalyze this reaction when pyruvate is
present in the biofuel cell solution. The oxidation leads to a transfer of
electrons to the electrode, producing power to turn on the sensor, leading to a
positive signal.
Since pyruvate is in the fuel
cell solution, one would expect a positive signal all the time. However,
mitochondria naturally have many inhibitors that prevent them from processing
biofuels. Oligomycin is one such inhibitor that shuts down power
production—conveniently, nitroaromatics, common explosive materials, reverse
this inhibition. Thus, by adding the inhibitor to a biofuel cell, a sensor is
created, as significant power production will only occur when enough explosive
chemicals are present to release the inhibition.
Minteer's sensor was able to
detect explosives present in concentrations as low as one picomolar. In the
presence of nitroaromatics, the sensor showed a 40-fold increase in power
density compared to the inhibited state. The signal for the presence of
explosives is no different if the concentration is 1 picomolar or 1 millimolar,
so it only works as a threshold sensor, providing just a on or off signal.
Minteer hopes that further engineering will allow concentration-specific
detection, as well.
Minteer's research team
successfully demonstrated that the unique properties of mitochondria have
applications far outside of biology. She predicts that a mitochondria-catalyzed
biofuel cell can "be used as a traditional electrochemical sensor or in
the self-powered sensor design."
J. Am. Chem. Soc.,
2008. DOI: 10.1021/ja807250b
