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A magnetic microbot can access traction and cell stiffness

Scientists have developed a tiny mechanical probe that can measure the inherent stiffness of cells and tissues. It can also measure the internal forces the cells generate and exert on one another. Their new “magnetic microrobot” will aid in understanding cellular processes associated with development and disease.

Their new “magnetic microrobot” is the first such probe to be able to quantify both properties, the researchers report, and will aid in understanding cellular processes associated with development and disease. They detail their findings in the journal Science Robotics. “Living cells generate forces through protein interactions, and it’s very hard to measure these forces,” said Ning Wang, a professor of mechanical science and engineering at the University of Illinois at Urbana-Champaign who led the research.

Such a probe would allow a better understanding of how these properties influence diseases like arteriosclerosis or cancer, or how an embryo develops, for example. To tackle this challenge, Wang and graduate student Erfan Mohagheghian looked for ways to alter the mechanical characteristics of a probe. But he said he wanted to develop a more universal probe that could tackle both at once. Such a probe would allow a better understanding of how these properties influence diseases like arteriosclerosis or cancer, or how an embryo develops, for example. To tackle this challenge, Wang and graduate student Erfan Mohagheghian looked for ways to alter the mechanical characteristics of a probe after injecting it into the tissue of interest.

Study co-author Kristi Anseth is a professor of chemical and biological engineering at the University of Colorado, Boulder. The team developed a precise method for embedding a magnetic “microcross” into a rigid PEG hydrogel. By subjecting those tissues to an electromagnetic field, the scientists activated the probes to exert various stresses on the tissues. The probes gave precise information about both the tissue stiffness and traction. While malignant tumors may become stiffer in response to surrounding tissues, the cancer cells do not change their tractions.

Researchers at the Chinese Academy of Sciences and Huazhong University of Science and Technology in Wuhan, China, have developed a magnetic microrobot that can detect force oscillations. Such oscillations correspond with the patterning of organs, tissues and limbs as animals develop from single cells into complex tissues.