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The Washington Research Foundation Fellowship

Leticia Huynh, Biochemistry - 2009-10 WRF/Space Grant

Leticia Huynh photoI entered the UW four years ago through the Robinson Center Early Entrance Program. since I was in elementary school I have known that I wanted to pursue a career in the health sciences and my initial experiences in general chemistry served to strengthen my interest in medical research. I decided to declare a major in biochemistry. During my subsequent introductory biology and organic chemistry classes I developed a deep interest in biotechnology. Two years ago I joined Dr. Daniel Chiu’s lab in the Chemistry Department in order to further explore biotechnology. The Chiu lab specializes in microfluidics, which is essentially the manipulation of miniscule amounts of fluid (on the order of microliters through femtoliters). Specifically, I work with microchips, which are polymer-based machines set with channels and other features that can be used to carry out chemical and biological reactions on a small scale.

After I graduate from UW, I hope to pursue an MD/PhD since I am extremely interested in the interface between the laboratory and the practice of medicine. Specifically, I hope to expand and apply my knowledge in microfluidics to my interest in infectious disease, perhaps by exploring how microfluidic technology can be used in a clinical setting.

In addition to majoring in biochemistry, I am pursuing a minor in history. I am also an Amgen Scholar and a member of the UW College Honors Program as well as the vice president of the UW Chapter of the Golden Key National Honor Society. I am a native resident of Seattle.  My hobbies include cooking, calligraphy, attending the ballet, and playing the piano. I also enjoy tennis, biking, and hiking.

Mentor: Daniel Chu, Chemistry

Project Title: Experimental Analysis of a pH Gradient-Induced Force on Charged Particles

Abstract: Due to the plentiful and diverse solutes found in cells, solute-solute interactions are an important part of cellular chemistry. In 2003, Zheng and Pollack observed that charged microspheres suspended in water avoided a region up to 100 μm away from a gel-water boundary. This suggests that solute-solute interactions extend for a much larger distance than previously believed. Although the mechanism of this “exclusion zone” phenomenon is unclear, one possible cause is the presence of a pH gradient around the gel-water boundary, which could have exerted a force on the charged microspheres directed away from the boundary. The Chiu lab seeks to test the viability of the pH gradient theory as an explanation of the exclusion zone phenomenon. The experiment is conducted on microfluidic chips, which are blocks of polymer engraved with channels, chambers, and other features and faced with glass. The experiment consists of two general stages: firstly, a pH gradient is established inside a microfluidic channel via the laminar flow of phosphate buffers with differing pH. Secondly, the behavior of charged microspheres is observed with respect to the pH boundary via microscopy. The preference of the charged microspheres for one side of the pH gradient would confirm pH gradients as the cause of exclusion zones, thus significantly contributing to current scientific knowledge of solute-solute interactions and cellular chemistry. Specifically, the forces caused by a pH gradient could be used to understand cellular chemotaxis: a cellular transport mechanism where the cells migrate towards areas of lower pH to escape their own metabolic waste products. Ultimately, this research could be the basis of a novel microfluidic purification method which uses pH gradients as the basis to separate the components of extremely small chemical mixtures by charge.