Silicon chip selectively collects and moves biological molecules, heralding cost-effective automated sample preparation for medical diagnostics
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Geneva,
November 30,2006 -
STMicroelectronics (NYSE), one of the world’s leading suppliers of
microfluidic devices, has announced that it has designed a complete prototype
device able to collect and manipulate specific biological molecules. Combined
with ST’s proven laboratory-on-chip technology, ST’s research project is paving
the way for the development of low-cost disposable chips that automate the
quick preparation, analysis and evaluation of medical and forensic biological
samples.
Current state-of-the-art biotechnological platforms such as ST’s
In-CheckTM “lab-on-chip” devices facilitate the diagnosis of
specific diseases or the monitoring of food and water for bacterial
contaminants by allowing the rapid detection of particular genetic material in
liquid biological samples. However, the preparation of the samples is still a
relatively time-consuming process performed with large samples in laboratories
using techniques that require skilled technicians and are difficult and
expensive to implement with smaller samples. The aim of the ST research program
is to explore new methods to automate sample preparation, so that the
biological molecules of interest could be rapidly extracted from “raw”
specimens such as saliva, blood or biopsy tissues and used as the input to the
lab-on-chip diagnostic stage.
“The market for diagnostic equipment is evolving towards fully automated,
cost-effective devices usable directly at the point of need,” said Maria Teresa
Gatti, Director of Research and Innovation, Advanced System Technology,
STMicroelectronics.
“Sample preparation technology, integrated with ST’s In-Check lab-on-chip
platform, will allow us to build low-cost, easy-to-use systems that will enable
diagnostic analyses to be performed outside specialized laboratories, e.g.
directly in hospitals or even in the doctor’s office,” noted Anton Hofmeister,
Group VP and General Manager, Microfluidics Division, STMicroelectronics.
The technique used by the ST researchers is based on a method called
dielectrophoresis, where an electric field is used to separate biological
particles contained in a conductive solution. The careful setting of physical
and electrical factors allows to precisely control the movement of target
particles and the aim of the ST project was to demonstrate that this could be
exploited for practical uses. Potential benefits include the ability to isolate
cells that are present in low concentrations, to increase the concentration of
cells in a solution and to extract DNA from the cell nucleus, as well as
allowing sample preparation to be performed in the field by personnel with
minimal training on the use of the devices. Importantly, the researchers also
successfully showed that by precisely controlling the voltage applied to
different electrodes, cells could be collected at one specific region and then
moved to other regions in either direction. The ST research project
builds on a prior joint research project between ST and Evotec Technologies
GmbH.
Details of the research project were unveiled at the NANOMEC06 Symposium on
Materials Science & Materials Mechanics at the Nanoscale, held at the
Politecnico di Bari, Italy in a paper presented by Marco Bianchessi, Sarah
Burgarella and Anna Zocco from ST’s Advanced Systems Technology (AST)
organization.
About STMicroelectronics
STMicroelectronics is a global leader in developing and delivering
semiconductor solutions across the spectrum of microelectronics
applications. An unrivalled combination of silicon and system
expertise, manufacturing strength, Intellectual Property (IP)
portfolio and strategic partners positions the Company at the
forefront of System-on-Chip (SoC) technology and its products play a
key role in enabling today's convergence markets. The Company's
shares are traded on the New York Stock Exchange, on Euronext Paris
and on the Milan Stock Exchange. In 2005, the Company's net revenues
were $8.88 billion and net earnings were $266 million. Further information on ST
can be found at www.st.com.
Information last updated Jan 2006
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TECHNICAL NOTES
- Dielectrophoresis is a phenomenon in which a spatially non-uniform electric
field exerts a net force on the field-induced dipole of an uncharged particle.
Particles with higher polarizability than the suspending medium experience
positive dielectrophoresis, and move towards regions of the highest field
gradient. Particles less polarized than the surrounding medium experience
negative dielectrophoresis, and move towards regions of low electric field
concentration.
- The system was built using a technology compatible with the
Micro-Electro-Mechanical System (MEMS) technology that ST uses for its
In-CheckTM lab-on-chip devices. The prototype silicon chip
contains a tiny channel, measuring about 1mm in length, 0.1mm in width and 50µm
in height (a human hair has a diameter of around 100µm) which is filled with a
solution containing the molecules of interest. On the bottom of the channel, an
array of tiny platinum electrodes (25µm wide, separated by 25µm) provides
precise control over the pattern of the electric field in the channel and
therefore the forces applied to the biological molecules.
- The operation of the prototype system was tested using a mixture of human
white blood cells (B-lymphocytes) and microscopic polystyrene beads of similar
size suspended in a Phosphate-Buffered Saline (PBS) solution. Without any
applied voltage, the B-lymphocytes and polystyrene beads were randomly
distributed in the channel. With an electric signal applied to the electrode
array, white blood cells collected at the electrode edges, separating from the
polystyrene beads suspended in the same PBS solution. The researchers observed
particle motion using a standard direct microscope with a video camera mounted
on it.
- The technology is covered by ST-Evotec patent applications 05108445.7
(Europe) and 11/531679 (USA).
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