AFM Measures Mechanical Properties of Living Cells
WEST LAFAYETTE, Ind., Nov. 22, 2011 — A new atomic force microscope (AFM) technique that measures the mechanical properties of living cells could be used to diagnose human disease and better understand biological processes.
Researchers from Purdue University and the University of Oxford have used the technique to study three distinctly different types of cells to demonstrate the method’s potentially broad applications.
Their paper, titled “Mapping Nanomechanical Properties of Live Cells Using Multi-harmonic Atomic Force Microscopy,” has been posted online in Nature Nanotechnology and will appear in the December print issue.
”There’s been a growing realization of the role of mechanics in cell biology and indeed a lot of effort in building models to explain how cells feel, respond and communicate mechanically both in health and disease,” said scientist Sonia Contera. She added that the group has provided a tool to start addressing some of these questions quantitatively.
This artist’s conception depicts the use of an atomic force microscope to study the mechanical properties of cells. Here, three types of cells are studied using the instrument: a rat fibroblast is the long, slender cell in the center, an E. coli bacterium is at the top right, and a human red blood cell is at the lower left. The colored portions, representing the mechanical properties of the cells, show the benefit of the new technique. The gray portions represent what was possible using a conventional approach. (Image: Purdue University/Alexander Cartagena)
An atomic force microscope uses a tiny vibrating probe to yield information about materials and surfaces on the scale of nanometers, or billionths of a meter. Because the instrument enables scientists to “see” objects far smaller than is possible using light microscopes, it could be ideal for “mapping” the mechanical properties of the tiniest cellular structures.
”The maps identify the mechanical properties of different parts of a cell — whether they are soft or rigid or squishy,” Arvind Raman said. “The key point is that now we can do it at high resolution and higher speed than conventional techniques.”
The high-speed capability makes it possible to watch living cells and observe biological processes in real time. Such a technique offers the hope of developing a “mechanobiology based” assay to complement standard biochemical assays.
”The atomic force microscope is the only tool that allows you to map the mechanical properties — take a photograph, if you will — of a live cell,” Raman said.
However, existing techniques for mapping these properties using the atomic force microscope are either too slow or don’t have high enough resolution.
“This innovation overcomes those limitations, mostly through improvements in signal processing,” Raman said. “You don’t need new equipment, so it’s an economical way to bump up pixels per minute and get quantitative information. Most importantly, we applied the technique to three very different kinds of cells: bacteria, human red blood cells and rat fibroblasts. This demonstrates its potential broad utility in medicine and research.”
The technique is nearly five times faster than standard atomic force microscope techniques.
It could be used to study how cells adhere to tissues, which is critical for many disease and biological processes; how cells move and change shape; how cancer cells evolve during metastasis; and how cells react to mechanical stimuli needed for production of vital proteins.
The method also could be used to study the mechanical properties of cells under the influence of antibiotics and drugs that suppress cancer.
For more information, visit: www.purdue.edu
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