John Bennet Fenn was born in New York City on June 15, 1917. He received a B.A. in Chemistry from Berea College and earned a Ph.D. in chemistry at Yale University three years later. Fenn spent over a decade in industry, first at the Monsanto Chemical Co. in Anniston, Alabama, and later at Experiment Incorporated in Richmond, Virginia, where his work led to employment as the director of Project SQUID, an Office of Naval Research program focused on jet expansions.

His first faculty appointment came in 1957 at Princeton University as a Professor of Aerospace Sciences; he returned to Yale in 1967 as a Professor of Applied Science and Chemistry. During his tenure at Yale, Fenn’s research focused on molecular beam and supersonic jet expansion experiments. Presented by colleagues with the problems involved in ionizing large biomolecules for mass spectrometric analysis, John Fenn, at nearly 65, embarked on a new research trajectory, one which would lead to the development of a practical electrospray ionization source.

In 1994 he moved his research lab to Virginia Commonwealth University where he was appointed Research Professor of Analytical Chemistry. This move allowed Fenn to continue his research program, producing more than 20 additional papers. It also provided the opportunity to interact with students and faculty on a daily basis, as he continued to inspire undergraduates, graduate students, postdocs and colleagues.

Fenn’s research garnered wide recognition across a variety of fields with the ultimate honor being a share of the 2002 Nobel Prize in Chemistry for his development of electrospray ionization mass spectrometry.

Fenn’s professional honors include:

• ASMS Distinguished Contribution Award (1992)
• ACS-DAC award for Advances in Chemical Instrumentation (2000)
• Election to the American Academy of Arts and of Science (2000)
• Thompson Medal from ISMS (2000)

Electrospray ionization mass spectrometry (ESI-MS) shows how a technical
breakthrough can reshape science and medicine. In the mid-1980s, John B. Fenn’s
group at Yale set out to do something that seemed nearly impossible at the time:
bring intact, fragile biomolecules into the gas phase for mass spectrometric analysis.
I had the privilege of working in his lab as a young scientist, witnessing the experiments that led to electrospray ionization - a gentle method that opened up the molecular world of proteins. For this discovery, John Fenn received the Nobel Prize in Chemistry in 2002.

This lecture will follow the trajectory from those foundational experiments to today,
where ESI-MS drives modern proteomics and is entering clinical practice. Mass
spectrometry can now quantify thousands of proteins from tiny samples, uncover
post-translational modifications, and map protein changes across tissues in health
and disease. Spatial proteomics approaches reveal how cancer cells interact with
their microenvironment. Scalable plasma proteomics is being applied to large
population cohorts—including studies of pregnancy—to improve early diagnosis and treatment. Emerging technologies such as machine-learning-driven data analysis
and high-throughput drug-target mapping are accelerating discovery and bringing
proteomics closer to direct patient benefit.

The story of ESI-MS is still unfolding. What began as an elegant physical solution to
a tricky ionization problem now contributes to saving lives in the clinic—an enduring
testament to John Fenn’s vision and curiosity, and a reminder of how far a “humble
beginning” in fundamental research can go.