Email a Friend
Printer Friendly

Feeling up Cells

March 01, 2001

Locally resolved detection of cell signals with microelectrodes
No matter how small, a living cell does not have a uniform structure. Instead, it has „organs“,
called organelles, which are assigned various tasks. Even the „shell“ of the cell, its membrane, is
not uniform. Functional building blocks, such as ion channels, can be distributed unevenly over
the membrane. To be able to observe the physiological activities of an individual living cell at
specific locations is the challenge researchers in Bochum have set themselves.
With the help of microelectrodes it has already been possible to examine a number of
biological phenomena, such as the distribution of ion channels or the shuttling of messenger
substances, in individual cells. In order to do this, the microelectrode must be brought very close
to the cell – either manually or with piezo-driven micromanipulators. The electrode is moved
toward the cell until it touches the membrane and is then pulled back to an exact distance. This is
not a satisfactory method, as the electrode can get contaminated, the cellular processes can be
disrupted or the cell can be destroyed. Also, the reproducibility leaves a lot to be desired.
Wolfgang Schuhmann and his team have developed a highly promising alternative. They use
a scanning electrochemical microscope equipped with a specially manufactured superfine carbon
fiber electrode. The crucial thing is that the electrode is made to vibrate: as the distance between
the electrode and the cell surface decreases, shear forces dampen the vibrations. The changes in
the vibrations can be measured with the help of a laser. This allows the researchers to keep the
distance from the cell – about 0.0001 mm – controlled and constant.
When the researchers scan the cell surface with their novel apparatus while recording the
deflection of the electrode, they obtain a topological picture of the living cell – without disturbing
it. The electrode can thus be placed in a precise location on the cell. Active agents can then be
introduced through a glass capillary, and the cell’s reaction, such as the release of
neurotransmitters, can be monitored with the electrode. After a rest phase the measurement can
be repeated at another location on the cell.
„Our next goal is to further decrease the diameter of the electrode, because this limits the
local resolution,“ says Schuhmann. „We also hope to use this to learn about metabolic reactions
in cell substructures.“

RSS Feeds

Feeling up Cells

Science Research Departments