Activity Report 2010 - CNRS

MEDICAL
APPLICATIONS OF THE
NANOBIOSCIENCES
SCIENTIFIC REPORT
FURTHER READING:
Optical Materials (2011)
Development of a non-linear optical
microscope for real-time measurement of
neuronal activity in sub-micrometric
structures
Fig. 2: Principle (top) and realization (down) of
the formation of lipid bilayers by bringing
together two nanodroplets covered with
phospholipids.
In 2010, the team already demonstrated
the formation of a lipid bilayer, as shown
by the large increase of capacitance.
Furthermore, incorporation of hemolysin,
a pore-forming protein, in the bilayer
membrane results in current steps
characteristic of single molecule activity.
This device will therefore offer an
alternative to electrophysiological “patchclamp”
methods using microelectrodes -
a process which is difficult to miniaturize
and automate.
Second harmonic imaging
of potentials in nanoscale
neuronal structures
“New comers” Project 2007: Julien
DOUADY (LIPhy)
Post doctoral fellow: Hartmut WEGE
The electric activities of neurons trigger
neurotransmitter release at synapses that
are small structures of about 200 nm. In
order to measure individual synapse
activation, neuroscientists use voltage
dependent fluorescent dyes. In this
project, such a series of dyes suitable for
two-photon activation has been
synthesized by the ENS-Lyon “Chemistry
for Optics” group. The Motiv group at the
LiPhy has built a custom two-photon
microscope to image neuronal activity
within brain slices, with a radial
resolution of about 340 nm (Fig. 4). To
address the actual challenges in
neurosciences, the sensitivity of the
setup will be improved to allow imaging
at about 2 kHz.
In the future, cell communication and
potential propagation within a brain slice
or cultured neurons will be studied.
Thanks to this ongoing multidisciplinary
project, the Grenoble neurophysiologist
community now possesses a new
powerful instrument to study neural
networks, either in micropatterns or in
brain slices.
Fig. 3: recording of -hemolysin activity
reconstituted in the Nanobiodrop device, the
15 pA current increase represents the
incorporation of one active protein molecule in
the bilayer.
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Fig. 4: Two-photon fluorescence imaging of
pyramidal neurons located 70 µm inside in a
300 µm thick sagittal slice of the mouse
cortex, stained with a voltage sensitive dye.
Note that the interspacing glial cells are not
stained. Barscale: 10 µm