University of Illinois researchers are using a new kind of microsensor to determine the relationship between cell mass and growth rate. Each microsensor is a 50 µm wide, suspended platform made in silicon on a chip. The suspended scale vibrates at a particular frequency, which changes when mass is added. As a cell's mass increases, the sensor's resonant frequency goes down.
The researchers, led by electrical and computer engineering and bioengineering professor Rashid Bashir, developed an array of hundreds of these microsensors on a chip. They can culture cells on the chip similar to the way scientists grow cells in a dish, allowing them to collect data from many cells at once, while still recording individual cellular measurements.
Another advantage of these microsensors is the ability to image cells with microscopes while cells grow on the sensors. Researchers can track the cells visually, opening the possibilities of tracking various cellular processes in conjunction with changes in mass.
Through measurements of live and fixed cells, the researchers were also able to extract physical properties such as stiffness through mathematical modeling. Some cell types are stiffer than others; for example, bone cells are more firm, while neurons are more gelatinous. Mechanical science and engineering professors Narayana Aluru and K. Jimmy Hsia, co-authors of the paper, performed extensive analytical and numerical simulation to reveal how cell stiffness and contact area affect mass measurement.
With their small, sensitive microsensors, the Illinois researchers were able to track individual colon cancer cells' masses and divisions over time, a feat never before accomplished. They found that the cells they studied did grow faster as they grew heavier, rather than growing at the same rate throughout the cell cycle.
Next, the researchers plan to extend the study to other cell lines, and explore more optical measurements and fluorescent markers.
"These technologies can also be used for diagnostic purposes, or for screening. For example, we could study cell growth and mass and changes in the cell structure based on drugs or chemicals," Bashir said.
The National Science Foundation supported this work. Other co-authors of the paper were post-doctoral associates Kidong Park, Larry Millet and Xioazhong Jin; mechanical science and engineering graduate students Namjung Kim and Huan Li; and electrical and computer engineering professor Gabriel Popescu.
Source: University of Illinois
Posted by Lee Mather
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