(10j) Nonequilibrium Biophysics and Rheology of the Inner Cell

Authors: 
Brady, J. F., California Institute of Technology
Research Interests:

The interior of a living cell is a dense, colloidal suspension containing a complex network of interacting protein machines that carry out lifeâ??s essential functions. My research focuses on understanding emergent properties and nonequilibrium processes of the inner cell at the colloidal and molecular scale. I invoke concepts from fluid mechanics, statistical physics, and molecular biophysics to develop mathematical and experimental tools to interrogate the complex hydrodynamic and biochemical processes occurring inside an active cellular cytoplasm.

As a doctoral student, I have developed frameworks to explain the collective motion of living systems, as in bacteria colonies, insect swarms, bird flocks, and fish schools. Using analytical theory and computer simulations, my research has revealed that all active matter systems generate a unique mechanical pressure, which is the fundamental physical mechanism that controls collective behavior, self-assembly, and pattern formation. This work was important because the understanding of how collective patterns of self-organization emerge from the joint interactions of active individuals has been a challenging problem in soft matter. Furthermore, the same phenomena of collective motion also occur inside a living cell, so my micromechanical model may be used to understand the rheology of active and living suspensions.

My research has evolved from its origin as a simple theoretical and computational framework to one that describes specific biological systems, like the cell interior where confinement plays a key role in the behavior of active motor proteins. I have developed lab experiments to encapsulate proteins, ions, macromolecules, synthetic active particles, bacteria, and other nano/micron-sized objects inside of a phospholipid vesicle, in an effort to create systems that operate close to the biophysical and physiological constraints of a living cell. I corroborate experimental data with Brownian/Stokesian dynamics simulations to understand the mechanical interactions governing intracellular transport within the cytoplasm.

My future research will involve analytical theory, stochastic simulations, and lab experiments to understand molecular-level transport phenomena in complex biological systems. I will use single-molecule manipulation techniques like optical/magnetic tweezers and atomic force microscopy to study the relationship between the mechanical forces that activate protein motors to the macroscopic behavior of a cell. I intend to pursue microrheology measurements to ascertain how motor proteins may be used as drug delivery targets for treatment of human diseases.

Recent experimental work will be the focus of my oral presentations at this meeting.

Selected publications:

  1. Takatori SC, De Dier R, Vermant J, Brady JF. Nature Commun. 2016; 7:10694.
  2. Takatori SC, Brady JF. Curr Opin Colloid Interface Sci. 2016; 21, 24.
  3. Takatori SC, Brady JF. Soft Matter.  2015; 11, 7920.
  4. Takatori SC, Brady JF. Phys Rev E. 2015; 91, 032117.
  5. Takatori SC, Brady JF. Soft Matter. 2014; 10, 9433.
  6. Takatori SC, Yan W, Brady JF. Phys Rev Lett. 2014; 113, 028103.

 

Teaching Interests:

I am excited to teach a variety of chemical engineering courses as a faculty member, in particular momentum, heat, and mass transfer at the undergraduate and graduate levels. In addition to transport phenomena, I am interested to teach statistical thermodynamics, soft matter physics, and mathematics and numerical methods for engineers and scientists. As a passionate public speaker, I value scientific communication and always strive to deliver coherently articulated lectures inside the classroom.


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