ACS Awards Priestley Medal to Frances Arnold

The American Chemical Society (ACS) has announced that it will honor Frances Arnold, the Linus Pauling Professor of Chemical Engineering, Bioengineering and Biochemistry and director of the Donna and Benjamin M. Rosen Bioengineering Center at Caltech, with the 2025 Priestley Medal, the society's highest honor.

The ACS awards the Priestley Medal annually to a single individual for distinguished services to chemistry. Arnold is being honored, according to a written statement from the ACS, "for her pioneering contributions to the development of directed evolution as a method for chemical and biological design." She will receive the medal and deliver an address on March 25 at ACS Spring 2025 meeting in San Diego, California.

Arnold, who won the Nobel Prize in Chemistry in 2018 and is co-chair of the President's Council of Advisors on Science and Technology, developed the novel bioengineering method known as directed evolution in the early 1990s for making new and improved enzymes in the laboratory using the principles of evolution. The method is now used in laboratories and companies around the world to make everything from laundry detergents to biofuels to medicines in more efficient and environmentally friendly ways. Enzymes created with the technique have replaced toxic chemicals in many industrial processes.

"I am deeply grateful for this recognition that nature's catalysts are pointing toward a chemical future that is clean, efficient, and sustainable," says Arnold. "Enzymes are the best chemists, of course, but the list of previous Priestley Medal winners is quite impressive."

Arnold earned her bachelor's degree in mechanical and aerospace engineering from Princeton University and her doctoral degree in chemical engineering from UC Berkeley. She joined the Caltech faculty in 1987. Most recently, she became the director of the Donna and Benjamin M. Rosen Bioengineering Center in 2013 and the Linus Pauling Professor in 2017.

Arnold was the first woman to receive the 2011 Charles Stark Draper Prize from the National Academy of Engineering (NAE). She is among the small number of individuals, and the first woman, elected to all three branches of the National Academies: the NAE (2000), the National Academy of Medicine (2004; it was then called the Institute of Medicine), and the National Academy of Sciences (NAS; 2008). She received the 2011 National Medal of Technology and Innovation and was inducted into the National Inventors Hall of Fame in 2014. She has won numerous other awards, including the 2016 Millenium Technology Prize, the 2019 Bower Award for Achievement in Science, and the Society of Chemical Industry America's 2023 Perkin Medal.

She is a member of the American Academy of Arts and Sciences and the American Philosophical Society and is a fellow of the American Association for the Advancement of Science, the Royal Society, and the Royal Academy of Engineering. She was appointed to the Pontifical Academy of Sciences by Pope Francis in 2019.

"She is a distinguished scientist, a pioneering engineer, a wonderful role model for young men and women, and a successful entrepreneur who has had extraordinary impact on the way we think about chemical and biological design and the biotechnology industry," says David Tirrell, Caltech's Provost, the Ross McCollum-William H. Corcoran Professor of Chemistry and Chemical Engineering, and the Carl and Shirley Larson Provostial Chair at Caltech.

The Priestley Medal commemorates the life of British scientist Joseph Priestley, who discovered oxygen in 1774 and spent the last 10 years of his life in the United States. Previous recipients at Caltech include Peter Dervan (2022), Bren Professor of Chemistry, Emeritus; Jacqueline Barton (2015), John G. Kirkwood and Arthur A. Noyes Professor of Chemistry, Emerita; Ahmed H. Zewail (2011); Harry B. Gray (1991), Arnold O. Beckman Professor of Chemistry and founding director of the Beckman Institute; John D. Roberts (1987); Linus Pauling (1984); and George S. Hammond (1976).