Toyoichi Tanaka

Japanese American biophysicist

• Born: January 4, 1946
• Birthplace: Nagaoka, Niigata Prefecture, Japan
• Died: May 20, 2000
• Place of death: Wellesley, Massachusetts

Tanaka’s discovery of the phase transition of polymer gels initiated a new field of research, making it possible for scientists to see microscopic changes in a macroscopic way. Because the “smart gels” respond to stimuli by expanding and contracting exponentially, they are valuable for use in a wide variety of applications.

Primary field: Physics

Primary invention: Smart gels

Early Life

Toyoichi Tanaka (to-yo-ee-chee tah-nah-kah) was born in Nagaoka, Niigata Prefecture, Japan, on January 4, 1946, to Toyosuke and Shizu Tanaka. As a child, he enjoyed athletics and was competitive in swordplay, racing, and sumo wrestling. He played baseball in junior high school for a time before stopping to devote time to preparing for entrance examinations into a good high school. He graduated from the elite Hibiya High School in 1964 before entering the University of Tokyo. His growing interest in the sciences was due in part to the influence of his father, a chemistry professor. In 1968, Tanaka received a bachelor of science degree in physics, followed two years later by a master’s degree, and in 1973 a doctor of science degree, all from the University of Tokyo. In 1970, Tanaka married Tomoko Tahira. The following year a son, Kazunori, a graduate student in physics at the Massachusetts Institute of Technology (MIT) at the time of his father’s death, was born. In 1972, Tanaka began postdoctoral work in physics at MIT, working with Professor George Benedek. A daughter, Ayako, was born in 1974. In 1975, he joined the physics faculty at MIT, rising to the rank of professor (1982) and becoming the Morningstar Professor of Science (1997). During the 1980-1981 academic year, Tanaka was visiting professor at the Pasteur Institute in Strasbourg, France, and was the Rashmer lecturer at the University of Washington in 1987. He also contributed a number of articles to professional journals and was editor in chief of the periodical Polymer Gels and Networks in 1992.

Life’s Work

Tanaka was only in his thirties when he made his first big discovery, that of the phase transition of polymer gels. Through his experimentation, he was able to make important theoretical predictions about polymers; in so doing, he gave birth to a new field of research. In the mid-1970’s, he found that polyacrylamide gels had the ability to respond to minute changes in their environment—variations of temperature, light, magnetism, or electricity—by changing color or by expanding or contracting exponentially. Tanaka fine-tuned gels to undergo radical changes, or phase transitions, when they came in contact with chemicals or environmental variations. This ability to react radically to these environmental changes resulted in the polymer gels with which he worked being labeled “smart” gels.

Because of the properties of expansion and contraction, Tanaka’s gels are ideal for a number of practical applications in varied fields, such as in medicine, industry, and agriculture. In medicine, for example, when the appropriate gels are exposed to electricity, they may undergo a thousandfold increase in volume that allows them to function as artificial muscles when they are set in motion by a particular electrical pulse. They can also be programmed to release insulin when glucose levels drop below a certain point and used in other controlled drug release products. The gels are also being used in such products as long-lasting sunscreen and eyedrops. In industry, the smart gels have proven to be effective in the cleanup of oil spills and in the absorption and immobilization of toxic waste because they act as giantsponges. They may also act as molecular filters of various kinds. The gels are useful in personal care items such as diapers and certain cosmetic products in which they can hold and then release ingredients such as fragrances in response to the pH level of the skin. Agricultural applications are numerous as well.

As Tanaka’s research continued, he was able to elucidate the roles of the various chemical and physical forces found in natural and artificial polymers involved in the phenomenon of polymer folding, the process whereby a polymer’s linear chair of molecules crumple, or fold, into more solid shapes so that they can perform their microscopic functions within living organisms. Putting this knowledge to practical use, Tanaka helped many scientists and companies to realize the practical applications of his work. In fact, in 1992, he cofounded GelMed, Inc., and a sister company, Gel Sciences, Inc. These companies explored medical, cosmetic, commercial, and industrial applications for polymer gels. Tanaka later cofounded Buyo-Buyo, Inc., a company that concentrates on finding medical solutions for enhancing and extending human life. Of particular interest to him was the idea of using smart gels to build artificial muscles. In the latter years of his life, Tanaka focused his energies on trying to unravel the mysteries of the origin of life, with which he saw a direct connection with his gel research.

Tanaka was honored with a number of awards before his untimely death. While still in his thirties, Tanaka received the Nishima Memorial Prize in 1985, and the following year the Award of the Polymer Society of Japan. He became a fellow of the American Physical Society in 1992, and in 1993 he was awarded the Vinci d’Excellence in France. In 1994, he received the Inoue Prize for Science, awarded for his outstanding achievement in basic science and given annually to a scientist under age fifty. In 1996, he won both the R&D 100 Award and Discover magazine’s Editor’s Choice for Emerging Technology Award. In 1997, he was the winner of the Thirty-eighth Toray Science and Technology Prize from the Toray Science Foundation in Japan. He was a Nobel Prize nominee and was considered one of the frontrunners among Japanese scientists to win one in the future, had his life not been cut short.

Tanaka’s hobbies included jazz piano, guitar, shogi (Japanese chess), watching movies, reading, and tennis. On Saturday, May 20, 2000, he died of an acute myocardial infarction at age fifty-four, while he was playing tennis.

Impact

While the general public may have heard about Tanaka through his inventions and applications of his polymer gel research, especially that having to do with smart gels, it was his scientific research and discovery that may prove to have been his greatest contribution. Because of that research, countless numbers of later researchers, scientists, and inventors whom Tanaka himself never met may well benefit from his work for years to come. Nevertheless, it is undoubtedly his work with polymers, and his revolutionary discovery of smart gels in particular, that have assured him a lasting place in scientific discovery. The sheer number of practical applications as diverse as pollution-cleanup materials and cosmetics make his work important to an immensely wide variety of products.

In addition to Tanaka’s work with polymer gels, he also contributed to the body of knowledge regarding the still-elusive process of polymer folding, the process by which polymers do not stay in the lengthened forms in which they begin but instead break into various solid shapes so that they can perform their microscopic functions within living organisms. Tanaka’s elucidation of the roles, in polymer folding, of the various chemical and physical forces found in natural and artificial polymers led to numerous practical applications.

Not the least of Tanaka’s impact on the world of science was his work with students; many of them considered themselves fortunate to be able to work in Dr. Tanaka’s laboratory at MIT. He had the reputation of being a superb teacher who could hold students spellbound with his demonstrations.

In the final years before his death, Tanaka focused his energies on trying to unravel the mysteries of the origin of life. He could not accept the then current theory of the origin of life, and he died while pioneering a new frontier of science.

Bibliography

Bogdanov, Konstantin Yu. Biology in Physics: Is Life Matter? New York: Academic Press, 1999. This volume represents a special effort to bring together the information that would allow a nonbiologically-oriented scientist to appreciate the important role that physics plays in life sciences. Provides an introduction to biophysics for the nonspecialist. Presents an advanced-level overview of mechanisms that regulate a variety of processes in organisms ranging from bacteria to whales.

Gandhi, M. V., and B. S. Thompson. Smart Materials and Structures. New York: Chapman & Hall, 1992. Provides a comprehensive introduction to the field of smart materials and structures. Also presents a review of the subdisciplines of the field, including shape-memory materials, made possible in part by smart-gel technology. The multidisciplinary nature of smart materials is stressed. Concludes with a chapter on research issues confronting researchers in this field. Extensive bibliography.

Huang, Kerson. Lectures on Statistical Physics and Protein Folding. Singapore: World Scientific, 2005. The first section of this book contains a concise review of relevant topics in statistical mechanics and kinetic theory, addressing standard topics in the field. The second section develops topics relating to molecular biology and protein structure, with a view to discovering mechanisms that underlie protein folding, especially on the energy flow through the protein in its folded state.

Tanaka, Toyoichi, ed. Experimental Methods in Polymer Science: Modern Methods in Polymer Research and Technology. New York: Academic Press, 2000. Discusses, in three sections by several Chinese and Japanese scientists, the phenomena of light scattering, neutron scattering, and fluorescence spectrography. The last section, in particular, addresses applications of fluorescence spectrography to polymer science.