In this video Ron describes how cells can be selectively manipulated
and sorted according to their intrinsic electrical properties, using
gentle forces generated by applying radio frequency signals to
microelectrode arrays.
Background:
The forces acting on the cells shown in these two video clips are
known as dielectrophoretic forces, and require the use of
microelectrodes whose geometries have been designed to generate high
electric field gradients. Using microelectrodes is important because
they can generate the required field gradients using small applied
voltages that do not harm the cells or cause electrolysis.
Dielectrophoresis is therefore a non-destructive way to characterise or
manipulate cells. Also, because the dielectrophoretic forces that act
on a cell depend on its unique dielectric properties, the cells can be
selectively manipulated or sorted without tagging or labelling them with
magnetic beads or fluorescent labels, for example. Dielectrophoresis
can also be used to isolate or manipulate other biological particles,
such as bacteria, viruses, proteins, DNA and RNA.
In the first video, an example is given of how pancreatic cells can
be formed into an artificial cell structure for diabetes research. The
second video shows breast cancer cells separating from each other
according to stages of their cell division. To achieve such cell
sorting using current biological techniques would require fluorescent
labelling of the nuclear DNA, in order to distinguish those cells at the
early stage of their life cycle from those about to divide to form two
cells. At the electronic frequencies used in the examples shown in the
two videos, the dielectrophoretic force is sensitive to changes in the
capacitance and electrical conductance of the cell membrane. This is
being used to selectively isolate and characterise stem cells according
to their stages of differentiation. To be of clinical use, stem cells
should not be labelled.
Our current efforts are also directed towards extending the
electronic signals from radio frequencies up to VHF frequencies, where
the dielectrophoretic response of a cell depends on its internal
properties such as the conductivity of the cytoplasm and the relative
size of the nucleus to the cytoplasm volume. The hope is that increased
cell sorting efficiency can be achieved by combining the radio
frequency selectivity based on cell membrane properties with that
achieved at VHF based on the cell’s internal properties.
Find out more:
Professor Ron Pethig, School of Engineering profile: http://www.eng.ed.ac.uk/about/people/prof-ronald-pethigEdinburgh Research Explorer:
http://www.research.ed.ac.uk/portal/en/persons/ronald-pethig(8d73df59-8206-4089-bca3-db2f1554ec3b).h...