Professor Mihoko Maruyama, Graduate School of Engineering
"Crystalline connections - A grand research journey transcending disciplines with colleagues"
Crystals are found everywhere in our daily lives. Tissues such as teeth, bones, and stones are crystals, semiconductor materials can be traced back to crystals such as silicon, gallium nitride (GaN) and silicon carbide (SiC) etc., and structural analysis of proteins, which is indispensable for drug discovery, is performed by crystallizing proteins. The interesting thing about this world is that when you look at it from the perspective of crystals, you begin to see connections between seemingly unrelated things.
Saving the earth and solving social problems with a crystalline cure
The origin of my career is my study in the field of earth science. When I was in elementary school, I was concerned about the deterioration of the global environment and thought, "I want to become a doctor who can cure the earth!” This ended up being the path I decided to follow. My eyes turned to crystals when I met Professor Katsuo Tsukamoto in geology, my mentor when I was an undergraduate student. When I asked him if he could help me conduct research on how to reduce CO2 emissions on the earth, he responded with this advice: "Crystallize CO2.” Looking back on it now, it seems like an outlandish suggestion, but at the time I was convinced and began researching crystals.
The prototype for my style of connecting all fields of research through crystals and conducting joint research was developed in his laboratory, where members conducted research on a variety of topics. With my feet firmly planted on the foundation of earth science, I was able to deepen my learning with peers who had different specialties, no longer restricted to my own field.
Professor Yusuke Mori's laboratory in the Graduate School of Engineering further expanded this "connected” attitude. The goal of the laboratory is to create crystals that have the potential to solve social problems, namely gallium nitride, the most promising crystal at the moment, with the highest possible quality. Professor Mori's idea was that if the technology was needed in another field, we would expand it horizontally. When I was studying earth science, I gained insight into things on a long-term scale of millions of years, but the laboratory faces "issues in the present.” We try every possible method in order to create the necessary crystals, but if this isn’t possible, we bring in someone with the technology. My days spent making crystals with such a mindset helped me to develop an attitude that transcends the larger frameworks of academia, industry, and medicine.
Creating an array of crystals develops abilities that connect several different fields
I am now mainly engaged in research on biomineralization, which is the crystallization of teeth, bones, shells, and other crystals, making use of my technology for producing useful crystals and analytical skills for extracting useful information from crystals. The crystallization mechanism in nature is truly mysterious. For example, the human body in its growth stage produces crystals such as teeth and bones that are convenient for us in a well-controlled manner. As we age, however, we do not make enough bone and develop osteoporosis, and sometimes crystallization progresses in unwanted places and we end up with urinary tract stones. It is strange that even though bone fractures do not heal quickly, crystallization can progress as much as 1 cm per month in unwanted places. There are also organisms that can crystallize CO2 without difficulty. Calcium carbonate, a solidified form of CO2, is a component of coral and various shellfish shells. Despite being difficult for us to do with today’s scientific technology, these organisms are able to crystallize CO2 with relative ease under normal temperature and pressure, even creating large, complex structures.
Figure: Polarized microscopy image of the thin section of urinary tract stones
As I continued my research on creating crystals that are useful to humans by taking hints from the natural world and the activities of living organisms, I was approached one day by a renal/urologist involved in research on urinary tract stones: "If you can make crystals, can't you also dissolve them?" Looking at urolithiasis from the perspective of crystals, I came to the realization that urinary tract stones and meteorites are similar. In the field of geology, we observe how meteorites crystallize and grow along a time axis. In the same way, if we observe how urinary tract stones have grown, we may be able to understand their growth history and establish a treatment method to dissolve stones in the body. With this in mind, we are engaged in this joint research [1].
Currently, I’m working with a research group on Urology and a confectionery company to develop snacks and supplements that prevent them. The project is called "METEOR,” which is an acronym for "Medical and Engineering Tactics for Elimination Of Rocks," suggesting the idea that urinary tract stones are like meteorites. It is very exciting to think that I, who am involved in the seemingly niche field of crystals, may be contributing to the development of confectionery products that are beneficial to health, and that these products may be on the store shelves in the near future.
We are also currently developing other forms of joint research by utilizing the "power of connection” to expand our research into all fields through the keyword "crystal," including research to create functional crystals that can be used as materials for new semiconductors and protein crystallization for structural analysis of proteins, which is the key to drug discovery.
Research is an “adventure” not unlike an RPG game, but to me it’s even more interesting than that. When I want to go somewhere or solve a particular problem, I look for colleagues that have abilities or skills that I do not. The real thrill of doing research is clearing the “dungeons” that await with the friends you have found in this way. Often a path that looked like a dead end to me can easily be thwarted with an idea from a colleague, or perhaps an unexpected detour can be found. When I arrive at a place that I could not have reached alone, it’s as if my colleagues and I are standing at the edge of the world, taking in a view that no one else has ever seen. In other words, we are expanding the boundaries of human common sense and knowledge by our own hands. Together with my colleagues, I would like to continue to experience more of these wonderful moments. This is one of my dreams as a researcher.
In 2050, what does a "future society where life shines brightly" look like to you?
My goal is to achieve ambitious environmental improvements for reducing CO2 emissions through the power of biomineralization.
In 2050, I hope to be able to create aggressive environmental protection technology that reduces not only CO2 emissions, but also the CO2 found in the atmosphere itself. Crystallization of CO2 is an effective way to do this, but the drawback is that crystals grow slowly through human power alone. A clue to solving such an issue is the clarification of the crystallization mechanism of corals and shellfish, which can speedily solidify CO2. The discovery of such paradoxical knowledge will allow us to protect the earth by borrowing the very power it has produced. We are also expanding our joint research as a participant in the METEOR Project with, for example, Professor Michio Suzuki of the University of Tokyo, who is very famous for his elucidation of the formation mechanism of pearl oysters.
[1] Michibata, U., Maruyama, M., Tanaka, Y. et al. The impact of crystal phase transition on the hardness and structure of kidney stones. Urolithiasis 52, 57 (2024). https://doi.org/10.1007/s00240-024-01556-5
For further information, please refer to the List of publications.
Edit: Saori Obayashi, Christopher Bubb