CBE Doctoral Dissertation Defense: “Synthesis of Enzyme-Powered Motors using Microfluidics” (Jessica O’Callaghan)

This thesis addresses the fundamental questions surrounding the design and functional capabilities of enzyme-powered micromotors synthesized using microfluidic techniques. The research focuses on the development of these motors, made from artificial cell (protocell) scaffolds, and which seek to replicate the motion behavior of biological cells, investigating their propulsion mechanisms, motion directionality, and collective behavior. The thesis first describes the development of a microfluidic platform for the synthesis of polymer and polymer-protein-based protocells. This platform enables precise control over the size, composition, and functional properties of the protocells, demonstrating the versatility of microfluidics in the fabrication of complex microstructures. Next, a novel approach to creating urease-powered micromotors using double emulsion-templated microcapsules is presented. The study explores how surfactants used in the emulsion assembly step that integrate themselves into the microcapsule structure can reliably lead to autonomous motion, providing insights into the design principles that govern the efficiency of enzyme-powered motors prepared by droplet microfluidics. The thesis next investigates the directed motion of urease-powered motors in gradients of urea, revealing how these motors can be directed away from high concentrations of substrate, providing insights into how to control their motion in complex fluids. Finally, the thesis explores interactions between enzyme-powered (active) and passive particles, demonstrating how active particles influence the motion of passive ones. The findings of this dissertation significantly advance our understanding of enzyme-powered motors, offering new strategies for their design and application. The use of microfluidic technology for the synthesis of these motors opens up new possibilities for the precise control of their properties, paving the way for their use in a wide range of scientific and technological applications.