A research team at the University of Tokyo has developed a new microscopy platform that can observe a previously hidden layer of biomolecular chemistry linked to weak magnetic fields.
The work was led by Project Researcher Noboru Ikeya and Professor Jonathan R. Woodward at the Graduate School of Arts and Sciences. Their method addresses a long-standing technical gap in life-science measurement: many important intermediates in spin-dependent reactions are "dark" molecules that do not emit light directly and therefore escape conventional fluorescence imaging.
To solve this, the team combined two precisely timed light pulses with a synchronized nanosecond magnetic pulse. The approach, called pump-field-probe fluorescence microscopy, compares signals as the magnetic field switches at different point in time. This comparison isolates the spin-dependent part of the chemistry and reveals precisely how magnetically sensitive intermediates appear and disappear.
The researchers validated the method in flavin-based model systems that are widely used to study biologically relevant photochemistry. They showed that the platform can recover reaction lifetimes and magnetic responses with high sensitivity, including at low concentrations matching cellular conditions. The system was capable of detecting very small signal changes under practical low-damage single-experiment per frame settings, an important step toward future live-cell studies.
More broadly, the study offers a new bridge between fluorescence microscopy and spin chemistry. It provides researchers with a way to probe molecular events that were previously inferred only indirectly, helping clarify how weak magnetic fields may influence biological processes. The team expects the method to accelerate research in quantum biology and to support future exploration of noninvasive diagnostic strategies based on spin-sensitive molecular behavior.
In the near term, the researchers plan to extend the platform to increasingly complex biological environments and to refine analysis pipelines for separating overlapping reaction pathways. By making dark, short-lived intermediates experimentally accessible, the method expands what can be measured in biological photochemistry and opens a practical route to studying magnetic effects at the molecular level.
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About The Graduate School of Arts and Sciences, College of Arts and Sciences, University of Tokyo
The Graduate School of Arts and Sciences, University of Tokyo, is affiliated with the College of Arts and Sciences. The College’s Junior Division educates first- and second-year undergraduates, offering cutting-edge instruction across the humanities, social sciences, and natural sciences. Building on this interdisciplinary foundation, the Senior Division supports third- and fourth-year students as they pursue broader academic interests, while the Graduate School advances innovative research.Find out more at https://www.c.u-tokyo.ac.jp/eng_site/ .
Journal of the American Chemical Society
Commentary/editorial
A Fluorescence Microscopy Platform for Time-Resolved Studies of Spin-Correlated Radical Pairs in Biological Systems
26-Mar-2026