Author: Marilynn Pharr Major: Biological Engineering 

For my honors research project, I worked with cellulose nanocrystals (CNCs). Cellulose nanocrystals (CNCs) are nanoscale particles that can be obtained from plants, marine animals, and other organisms. Due to the structural strength, biodegradability, and other properties of CNCs, these nanoparticles are used in biomedical applications such as drug delivery, scaffolds, and medical implants. For example, in Dr. Jin-Woo Kim’s lab, the Bio/Nano Technology Laboratory, they use CNCs by incorporating them into tissue engineering scaffolds which assist in tissue development. There are a variety of processes that are used to isolate CNCs from an assortment of materials that contain cellulose, and researchers have used different methods to calculate the yield. The yield of a specific production process is a measure of the amount of CNC particles that can be obtained from a certain amount starting material. In order to compare the ways of isolating CNC from varying materials, using one method to determine yield would make it easier to compare the processes as well as efficiency of the process. The goal of my research was to compare different methods used to determine yield when extracting cellulose nanocrystals.  

My interest and knowledge of CNCs were rooted from the research experience for undergraduates (REU) program I participated in last summer. With the guidance of my advisor, Dr. Kim, I was able to work on a project that involved CNCs and that I could complete in my last two semesters of college. He also asked me what my post-graduation plans were because he wanted to tailor my project on to be valuable for my future plans. At that time, the beginning of the fall 2018 semester, I was not sure if I wanted to pursue graduate school or focus on finding a job, so we end up deciding on a project that would be not only beneficial to his lab but other labs as well.  

Throughout the entire process, I was thankful to have Ph.D. candidate Gurshagan Kandhola guiding me through all the lab work as well as writing my thesis. The first part of my research was to prepare the CNC samples from three raw materials: microcrystalline cellulose, sweetgum pulp, and pine pulp. In order to validate that the samples obtained were CNC, I was able to learn how to take transmission electron microscope (TEM) images of the sample and characterize the particles using dynamic light scattering (DLS). The four methods we used to measure yield were air-drying films, oven-drying films, freeze-drying the sample, and determining the chemical oxygen demand (COD) of the sample. Out of the four methods, air-drying and oven-drying films were the simplest methods. The freeze-dryer was newly bought, and the COD method had never been used in the lab, so Gurshagan and I both learned how to use the equipment as well as understand the concept of measuring COD. The hardest part of this project was the COD method, because it required understanding the chemical reaction and creating a calibration curve. We learned as we went through the COD method and end up collecting data that we didn’t need. After comparing the methods, we found that the oven-drying films method was the technique we recommended to determine yield, because it has statistically similar results to other methods and required the least amount of equipment and materials.  

Even though I will not be attending graduate school, I have thoroughly enjoyed working in the lab and learning more about the research process. One thing Dr. Kim had emphasized throughout my project, was understanding the motivation for the research. I thought this was an important point to make, not only in research, but in other engineering projects as well. I hope to take this piece of advice with me when I move to San Diego, CA to be a Sales Application Engineer for Solar Turbines, Inc.