Activity Report 2010 - CNRS

Innovative biochips to
detect and screen biological
cells
“Fil de l’eau” PhD student 2008:
Radoslaw BOMBERA
Thesis Directors: Thierry LIVACHE and
Yann ROUPIOZ (INAC/SPrAM).
The biological matter is a complex
mixture of cells and molecules. Selective
capture and release are therefore
necessary to sort and analyze cells, in the
blood for instance. In this project, living
cells are reversibly adsorbed on a
functionalized surface.
This technique could provide a low-cost
alternative to flow cytometry methods,
currently used in biology and medicine to
quantitatively analyze cell mixtures.
The development of these new biochips
combines different innovations:
using complementary DNA
strands to immobilize antibodies onto
surfaces; these antibodies can selectively
capture cells entering in contact with the
biochip surface.
locally heating up the surface to
dissociate DNA strands and releasing
cells; cells and molecules are both
detected by surface plasmon resonance
imaging.
Figure 5 shows a proof-of-concept
experiment. Three different probes are
used. The first two ones allow antibodies
to be immobilized, that in turn capture B
and T lymphocytes, respectively. The last
one is a negative control. The relative
reflectivity of a gold surface, which is
related to the mass adsorbed to the
surface of the biochip, is measured in
real-time.
In a) the coupling DNA strands bind to
the DNA probes, in b) the antibodies are
immobilized, in c) the cells are captured.
In d) and e) they are selectively released
from the surface using restriction
enzymes to cleave the DNA molecules.
Further work already demonstrated that
the local heating of the gold surface
provided by resonant plasmons induced
by laser illumination is sufficient to
induce DNA strand dissociation and their
release in the bulk solution. Studies are
ongoing to show that the released cells
are still viable and to analyze their
content.
a)
b)
Fig. 5: Kinetic curves of the gold surface
relative reflectivity detected by Surface
Plasmon Resonance Imaging.
Biomimetic artificial
membrane systems for
generating electro-chemical
energy
Chair of Excellence 2007: Don MARTIN
Coordinator: Philippe CINQUIN (TIMC-
IMAG).
One of the bottlenecks in the
development of implantable prostheses
and devices is the lack of small size
electric sources. It is nevertheless well
known that certain fish possesses electric
organs able to generate powerful
discharges (tens of kW). The energy is
provided by large Na + currents flowing
rapidly through membrane channels into
stacked cells, similarly to the action
potentials generated in neurons and
muscle cells. It is therefore theoretically
possible to mimic these biological
processes and develop implantable
devices to harvest the energy resulting
from differences in ion concentrations
within the human body.
Thus, the objective of the project is to
develop new electrochemical energy
sources that are both biocompatible and
biologically-inspired. The core principle is
to reconstitute a supported biomimetic
bilayer membrane incorporating
transmembrane channels separating two
compartments with different ion
composition. Ion flow, driven by the
difference in ion concentration, will
accordingly provide the electro-chemical
energy of the device. A large contact area
(tens of mm 2 ) between the membrane
and the bathing fluids is necessary to
generate enough electrochemical energy,
but since the lipid bilayer is only 5 nm
thick, this active structure is extremely
fragile.
c)
d)
e)
FURTHER READING:
SCIENTIFIC REPORT
IET Nanobiotechnology,
vol. 4, n o 3, pp. 77-90 (2010)
Terminating polyelectrolyte in
multilayer films influences growth and
morphology of adhering cells
29