Chip gauges cell reactions
Technology Research News
cells react quickly and distinctly to many types of stimuli, including antibiotics,
radiation, pathogens, and chemicals.
Researchers from the State University of New York at Buffalo have
devised a way to test within minutes the reactions of cells to all types
of stimuli. The researchers' system is very sensitive, relatively inexpensive,
uses little power, and is portable.
Key to the technique is the connection between a cell's volume and
The method could eventually be used to screen cells and portions
of cells to evaluate their reactions to stresses like radiation and chemicals,
said Frederick Sachs, a professor of physiology and biophysics at the State
University of New York at Buffalo. It could gauge, for example, the effectiveness
of chemotherapy or radiation protocols on human cancer cells, he said.
The silicon chip sensor measures electrical resistance. Cells are
electrical insulators, while saltwater conducts electricity. When cells
are put in a container of saltwater they displace some of the water, increasing
the resistance within the container. A cell tends to swell in the presence
of a toxin, displacing more of the saltwater, which measurably increases
the container's electrical resistance.
Lab devices that measure cell volume exist, but are larger and slower
than the researchers' microfluidic device.
The researchers' prototype is a silicon wafer with a 1.5-millimeter-wide,
15-micron-deep channel that connects a pair of chambers. One chamber is
the same depth as the channel; the other is 55 microns. Each chamber contains
four platinum electrodes that measure electrical resistance. The shallow
chamber measures cell volume and the deeper chamber calibrates the device
by measuring the electrical resistance of the fluid.
The technique is faster and simpler than microfluidic devices that
measure cell growth, and it provides direct observation of changes to cells,
said Sachs. It can be used to measure cells and parts of cells like organelles
and lipid vesicles, he said.
The prototype allowed the researchers to assess the sensitivity
of different strains of E. coli bacteria to antibiotics within ten minutes
at room temperature, said Sachs. "It is rare that we come up with something
so general and so simple that is still useful," he said. "But simplicity
is critical for reliable assays."
The method could be adapted to screen many samples at once by automating
the fluid handling and temperature control and adding robotics to automate
the process, said Sachs.
The sensor could be used practically in one to five years, said
Sachs. The next steps are to simplify sample placement and to automate fluid
and temperature control, he said. The technology must also be implemented
in plastic and interfaced with robotics to adapt it for commercial high-throughput
use, he added.
Sachs's research colleagues were Daniel A. Ateya, Philip A. Gottlieb,
Steve Besch, and Susan Z. Hua. The work appeared in the January 22, 2005
issue of Analytical Chemistry. The research was funded by the National
Institutes of Health (NIH) and the National Science Foundation (NSF).
Timeline: 1-5 years
TRN Categories: Microfluidics; Biotechnology; Sensors
Story Type: News
Related Elements: Technical paper, "Volume Cytometry: Microfluidics
Sensor for High-Throughput Screening in Real-time," Analytical Chemistry,
January 22, 2005
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