In addition to its annual lectures, ChBE hosts a weekly seminar throughout the year with invited lecturers who are prominent in their fields. Unless otherwise noted, all seminars are held on Wednesdays in the Molecular Science and Engineering Building ("M" Building) in G011 (Cherry Logan Emerson Lecture Theater) at 4 p.m. Refreshments are served at 3:30 p.m. in the Emerson-Lewis Reception Salon.

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"Lava Lamps, Hopscotch and Enzymes: A Toolbox for Chemical Engineering at the Microscale"

Victor Ugaz, Associate Professor, Artie McFerrin Department of Chemical Engineering, Texas A&M University

Abstract:
I will describe recent work in our research group aimed at harnessing fundamental transport phenomena at the microscale in ways that can help enable the development of rapid portable bioanalysis systems. First, I will introduce a novel method to actuate DNA replication via the polymerase chain reaction (PCR) by exploiting thermally driven natural convection. This implementation offers advantages including an inherently simple design (similar to a lava lamp) and minimal electrical power consumption (important for portable applications). We have probed the 3-D velocity and temperature distributions inside microscale convective reactors, and unexpectedly discovered a subset of complex flow trajectories where extremely rapid DNA replication rates are achievable due to the onset of chaotic advection. These surprisingly complex 3D flows are also able to function as highly efficient conveyors capable of continually shuttling molecular species from the bulk fluid to targeted locations on the solid boundaries, suggesting a new mechanism to explain emergence of complex biomacromolecules from dilute organic precursors in the prebiotic milieu—a key unanswered question in the origin of life.

Next, I will describe how the inherently disordered dynamics governing macromolecular transport in confined surroundings, conventionally suppressed as an undesirable noisy background, can paradoxically be precisely controlled. This ability lays a foundation for an entropic force microscope, a sensitive probe of nanoscale biomolecular conformation capable of resolving previously unseen details about DNA-protein binding interactions at size scales below the limits of conventional techniques. Finally, I will show how specific biochemical interactions between an enzyme and a biodegradable substrate can be harnessed to execute precise flow-actuated micromachining. This novel approach makes it possible to construct a microfluidic-based filtration device capable of performing simultaneous size-based isolation and enrichment of cells from whole blood. The underlying inertial flow phenomena are strongest at high flow rates, making our design ideally suited for high-throughput processing of large sample volumes.