Master of Science in Chemical Engineering (MSChE)
Harmful algal blooms pose a threat to human health and the environment. Many complex factors influence their formation and development, and much is still unknown. One major influencing factor that is well-known yet poorly studied is algal chemotaxis. Many studies have examined chemotaxis in other organisms, but very little about chemotaxis in algae has been studied, largely because existing technology and assay techniques are inadequate. Microfluidics offers many possibilities for cell biology, and has been applied to the study of chemotaxis in other organisms already. These techniques can be applied to the study of algal chemotaxis as well. We present in this study a flow-free microfluidic gradient generator for the study of algal chemotaxis. The device consists of a bottom layer of agarose hydrogel and a top layer of PDMS imprinted with thee parallel microchannels. A gradient is formed by flowing media containing a chemoeffector in one of the outer channels and a buffer solution in the other, providing two constant-concentration boundary conditions. The center channel is left flow-free to allow cells to migrate freely in response to the gradient. We demonstrate the device operation using Chlamydomonas reinhardtii as our model organism, exposing the cells to a gradient of nitrogen in the form of ammonium. We also further demonstrate the device’s utility by modifying it for use in long-term culturing of algal cells, with the ultimate goal of studying allelopathy by culturing two species side-by-side. The modified device contains a second cell culture channel, enabling us to culture two different cell populations that are chemically connected via diffusion but kept physically separate. As a proof of concept, we successfully culture C. reinhardtii first in a 3-channel device, then in both channels of a 4-channel device.
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Roberts, Benjamin Seth, "Development of Microfluidic Devices to Study Algal Chemotaxis and Long-Term Growth Dynamics" (2016). LSU Master's Theses. 4496.