As a chemist, Assistant Professor Ji Ha Lee from Hiroshima University's Graduate School of Advanced Science and Engineering works on developing recyclable and degradable gels sturdy enough to replace plastics as well as nanogels that can help with targeted drug delivery. We chatted with her to get to know more about her and her work.
Q: Can you please tell us about your field of research?
Ah, yes! My research focuses on gel materials. Do you know about gels?
Q: Yes, but we're not so familiar with it. Can you tell us about it?
Gels are not fully liquid nor solid but they behave sometimes like a liquid and sometimes like a solid. Think of konjac, contact lenses, and jelly.
They are a substance with a physical structure that can range from soft and weak to hard and rough. Gels are defined as a dilute cross-linked system that doesn't flow when in a steady state, appearing mostly like a liquid but behaving like a solid due to its three-dimensional cross-linked network structure. They are commonly found in different forms and have properties such as solvents, crosslinking points, and 3D network structures. Furthermore, the hardness and roughness of soft gels can be controlled through external stimulation, such as pH, temperature, and light. With these properties, gels have potential applications in various fields like medicine, food, and cosmetics.
Q: We wonder what got you into this field?
As a 4th-year undergraduate student, I joined a laboratory for my graduation experiment and knew about gel research for the first time. The laboratory mainly focused on creating sensors using fluorescent compounds in the presence of heavy metal ions such as mercury, lead, and cesium. However, the process involved many synthesis steps, which I found tedious. Instead, I chose to focus on gel research, which had a shorter and simpler synthesis process. My experiment was successful, and I was fascinated by the fluorescence and color changes that occurred during the gelation process from solution to gel in the presence of a metal ion. I also appreciated the versatility of gels, which could change from liquid to solid depending on the environment.
Q: Can you walk us through the scientific problem that this intrigue of gels has now led you to answer?
Yes. You see, the efficient utilization of resources requires materials that are easily recyclable and degradable. While polymers like plastics have various applications, they are hard to decompose due to the formation of numerous covalent bonds through polymerization reactions. However, since bonding strength and degradability are in a trade-off relationship, it is difficult to design a material in which these two characteristics are compatible. As a solution to these challenges, the creation of materials using interactions between molecules in supramolecular science is attracting attention.
The aim of my study is to develop a “sol-gel-gel plastic” with controlled mechanical strength and degradability through the introduction of covalent bonds for improved strength and supramolecular interactions for dissolvability in solution. The goal is to create a recyclable and degradable gel system.
Q: That could be good for the environment. Can you expound on that?
What I’m doing is utilizing technology that can accurately control the transformation from a soft material to a hard material — a new material developed as a replacement for plastic.
Q: Are there any breakthroughs you would like to share with us?
Our group has discovered that supramolecular gels made using calixarene exhibit superior mechanical properties compared to conventional polymer materials. These supramolecular gels have a tensile strength of 42 MegaPascals, meaning they can withstand 6092 pounds per square inch of pressure. They can stretch up to 0.86% of their original shape without breaking. And they can tolerate about 290 pounds per square inch of pressure and still spring back to their original form without deformations.
Q: Is there anything that surprised you the most in your research?
Well, in addition to developing alternative plastic materials, our research also focuses on utilizing gel systems for a drug delivery system (DDS). The goal of a DDS is to effectively deliver drugs to the desired target while minimizing side effects and maximizing efficacy. To achieve this, various drug carriers are used, including gel materials. Gel materials have the advantage of allowing precise control over the amount of drug encapsulation. Furthermore, the rate and amount of drug release can be adjusted by controlling the mechanical properties of the gel.
Recently, we successfully controlled the elasticity of a gel system made from chitosan, a natural polysaccharide, by precisely adjusting the concentration of a weak acid. The resulting stretchable gel was used to include a drug, and the release rate was found to be 90%, compared to just 10% in a non-stretchable gel. This demonstrates the potential for creating a new material that can release drugs at desired target sites in controlled amounts.
Q: You must be delighted with all these astonishing findings in your research. May we ask which achievement you are so far most proud of?
As a young researcher, I am still building my body of research and have not yet achieved a result that I can say I am particularly proud of. However, I am proud of the progress I have made through persistent effort and determination. A while ago, I watched “Slam Dunk” and was touched by how it showed the importance of not giving up until the end. I think experiments are similar. There are many times when I may want to give up during an experiment, but if I try to solve each problem one by one without giving up, I eventually succeed. These hard-won results stay with me for a long time and make me proud.
*Answers to the questions were edited for clarity and brevity.
About Hiroshima University
Since its foundation in 1949, Hiroshima University has striven to become one of the most prominent and comprehensive universities in Japan for the promotion and development of scholarship and education. Consisting of 12 schools for undergraduate level and 4 graduate schools, ranging from natural sciences to humanities and social sciences, the university has grown into one of the most distinguished comprehensive research universities in Japan. English website: https://www.hiroshima-u.ac.jp/en