(10p) Exploring and Exploiting the Physical Properties of Biological Soft Matter: From Bacterial Infections to Metastatic Cancer

Authors: 
Stewart, E. J., Massachusetts Institute of Technology

Research Interests:

The structural and mechanical properties of biological soft matter (i.e. biopolymers, cells, bacterial biofilms, tissues) are often connected to cellular function and disease state. However, there is frequently a gap in the understanding of the biomechanical contributions to systems level behavior. Determining the physical behaviors of biological soft matter contributes to addressing this knowledge gap and allows for the development of novel therapeutic tools targeting the physical properties of biological systems. Here I demonstrate the utilization of a soft matter approach to address two clinically relevant problems: a) bacterial infection prevention and control and b) minimally invasive cancer diagnosis and assessment.

Bacterial biofilms are structured communities of cells encapsulated in polysaccharides, proteins and DNA that are frequently responsible for clinical infections. In my work, I consider bacterial biofilms as a biocolloidal system, where the cells are analogous to colloidal particles and the matrix materials are analogous to a viscoelastic hydrogel. I find that unstressed staphylococcal biofilms have densely packed, disordered microstructures, while stressed biofilms contain open, tenuous, fractal-like microstructures. I create artificial staphylococcal biofilms and reveal the importance of pH and matrix phase behavior to biofilm mechanics and dispersal. I identify that multispecies staphylococcal biofilm structures and growth behaviors are strongly dependent on their growth environment. These findings on the structure and mechanics of biofilms have implications in the field of biofilm microbiology and in the practice of biofilm prevention and control.

Metastatic cancer is cancer that has spread from the original site to a more distant site within the body. Cancer metastasis is often initiated by circulating tumor cells (CTCs), cells that shed off of tumors and circulate in the blood stream. Here I demonstrate the use of microfluidic devices for the rapid and minimally invasive testing of the biophysical markers of cancer and its metastasis. Specifically, I report the utilization of a deformability cytometer for the high-throughput assessment of cancer cell mechanics and the use of label-free sorting devices to separate viable CTCs from blood using sound waves. These devices could serve as cancer diagnostics and prognosis assessments.

Through continuing to investigate the biophysical properties of cells and multicellular systems, I plan to reveal connections between the physical properties of living systems and their disease states and to utilize these findings to develop therapeutics and diagnostics.

Teaching Interests:

At the undergraduate level, I am most interested in teaching Material and Energy Balances, Mass Transfer, Heat Transfer, and Fluid Mechanics. I have previous experience teaching Heat and Mass Transfer, and concepts from Transport Phenomena and Fluid Mechanics are important to my research. I am also willing and able to teach any of the core chemical engineering courses as requested.

At the graduate level, I am most interested in teaching core courses like Transport Phenomena or Fluid Mechanics. I am also interested in developing graduate elective coursework in Biological Soft Matter, Principles and Applications of Colloidal Science, and Quantitative Imaging Methods.

Additionally, I plan to continue to conduct engineering education research. During my PhD, I researched student learning in an interdisciplinary graduate elective course.

Education:

Massachusetts Institute of Technology,  Postdoctoral Associate, Materials Science and Engineering, 2015â??Present

Project Title: Microfluidic Devices for Minimally Invasive Testing of Biophysical Markers of Cancer

Advisor: Dr. Ming Dao

University of Michigan, PhD, Chemical Engineering, 2015

Dissertation Title: Staphylococcal Biofilms: Microstructure, Mechanics, Self-assembly, and Multispecies Communities

Advisors: Professor Michael J. Solomon and Professor John G. Younger

University of Michigan, MS, Chemical Engineering, 2010

Worcester Polytechnic Institute, BS, Chemical Engineering, Minor in Materials Science, 2008

Keywords: Biological Soft Matter, Biomechanics, Bacterial Biofilms, Metastatic Cancer, Complex Fluids, Colloidal Science, Engineering Education, Interdisciplinary Learning

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