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technique for the pharmaceutical industry and to improve protein analysis tech-
niques. Potential applications of DEP for protein manipulation in the pharmaceu-
tical, analytical, and genetic fields are a large potential, more applications
employing protein DEP being demonstrated in the last 20 years [ 24 ].
Furthermore, it has also been demonstrated that it is possible to use DEP to
separate human breast cancer cells from blood, again because the dielectric prop-
erties of these differ significantly [ 25 ]. The advancement of these methods will
enable levels of control of biological systems that have not been achieved up to now
by any other method [ 23 , 26 ].
Recently, several attempts to use dielectrophoresis as a novel separation method
for nanoparticles with different chemical groups on their various surfaces
containing inorganic and polymer materials (Janus particles) were done
[ 27 ]. “Janus” particles (JP), named after the Roman mythology god (who possessed
two faces), are anisotropic dissymmetric particles, with two different physical/
chemical properties, including biphasic material, biocompartmental, dumbbell-
like, snowman-like, acorn-like, or half-raspberry-like particles (Fig. 14.4 ), and
offer new possibilities in microfluidic research fields [ 28 , 29 ]. They show particular
properties and their use is of great interest in biology or medicine diagnosis, an
active research field being the use of colloidal particles to sense and manipulate
cells that present specific proteins on their surface [ 30 ].
Janus particles proved to be capable to sense protein-cell interactions or to
organize cell on a substrate antigen-antibody interactions by adsorbing antigenes
on their polystyrene side, a fine control of their handling being demonstrated by
using DEP. The DEP manipulation of Janus particle coupled with a selective
grafting of proteins on one of their side could lead to a powerful tool regarding
protein-protein or protein-cell interactions studies. The grafting of proteins on a
single side of a JP is use to preactivate this side only with a molecule that will bind
the protein [ 24 ]. On the other hand, Janus particles demonstrate other multitude of
interesting effects in external electric fields, such as the assembly of targeted
Fig. 14.4 Schematic
representation of Janus and
comparable particles
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