Fast and High-resolution Dynamic Mechanical Spectroscopy of Biological Cells

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Dynamic mechanical spectroscopy allows measuring mechanical properties of materials at different speeds. It is a popular technique for studying soft material such as polymers. However, because of several intrinsic problems, this technique has not been extended to study the properties of biological cells as of yet. Besides fundamental interest, the study of cell mechanics makes a practical impact in understanding mechanical changes of cells in various diseases, like cancer, malaria, Alzheimer, and even aging. However, most cell studies were done for their static properties. While the changes in dynamic mechanical properties of cells are expected to be much richer, the existing attempts to measure cell dynamic properties have been very limited, and the results are controversial. This award supports fundamental research to provide knowledge needed for the development of a new quantitative technique to perform dynamic mechanical measurements of cells. The new method has the potential to revolutionize the study of cell mechanics. In general, it will also bring a new dimension to the study of the mechanics of biomaterials and nanocomposites at the nanoscale. It will expand the knowledge base to a scale of resolutions previously inaccessible. A translational part will include investigation of biomechanics of cancer cells. This application can build the foundation for nanomechanical applications in healthcare, which can benefit the U.S. society by saving billions of dollars through the early detection of cancer. The research will combine physics, biology, electronics, and nanotechnology. This multi-disciplinary approach will help broaden participation of underrepresented groups in research and positively impact mechanical and biomedical engineering education.Dynamic mechanical spectroscopy deals with the storage and loss moduli of materials which are the least model dependent quantities. While this method is standard for soft material, excessive time of measurements and low resolution preclude its use from obtaining reliable moduli on biological cells. In addition, cells are complex composite objects. This research will combine fast Fourier spectroscopy and atomic force microscopy to improve the speed and spatial resolution of dynamic mechanical spectroscopy. The improvement is expected to be more than 100x in speed and 100x in the resolution compared to the existing methods. The research team will apply this method to develop an appropriate viscoelastic cell model, in particular, taking into account pericellular brush, an important cellular organelle which dynamical mechanical properties are yet to be discovered. The obtained knowledge will be applied to study biomechanics of human cervical and breast cancer cells.