Despite myriad challenges, clinicians see room for progress.
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Edited by P. J. Hore, Oxford University, Oxford, United Kingdom, and accepted by Editorial Board Member Yale E. Goldman December 1, 2020 (received for review August 26, 2020)
Significance
The radical pair mechanism is the favored hypothesis for explaining biological effects of weak magnetic fields, such as animal magnetoreception and possible adverse health effects. To date, however, there is no direct experimental evidence for magnetic effects on radical pair reactions in cells, the fundamental building blocks of living systems. In this paper, using a custom-built microscope, we demonstrate that flavin-based autofluorescence in native, untreated HeLa cells is magnetic field sensitive, due to the formation and electron spin–selective recombination of spin-correlated radical pairs. This work thus provides a direct link between magnetic field effects on chemical reactions measured in solution and chemical reactions taking place in living cells.
Abstract
We demonstrate, by direct, single-cell imaging kinetic measurements, that endogenous autofluorescence in HeLa cells is sensitive to the application of external magnetic fields of 25 mT and less. We provide spectroscopic and mechanistic evidence that our findings can be explained in terms of magnetic field effects on photoinduced electron transfer reactions to flavins, through the radical pair mechanism. The observed magnetic field dependence is consistent with a triplet-born radical pair and a B1/2 value of 18.0 mT with a saturation value of 3.7%.
Footnotes
- ↵1To whom correspondence may be addressed. Email: jrwoodward{at}g.ecc.u-tokyo.ac.jp.
Author contributions: N.I. and J.R.W. designed research; N.I. performed research; N.I. and J.R.W. analyzed data; N.I. and J.R.W. wrote the paper; and J.R.W. conceived the project.
The authors declare no competing interest.
This article is a PNAS Direct Submission. P.J.H. is a guest editor invited by the Editorial Board.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2018043118/-/DCSupplemental.
Data Availability.
All study data are included in the article and supporting information.
Published under the PNAS license.
References
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Cellular autofluorescence is magnetic field sensitive
Article Classifications
- Biological Sciences
- Cell Biology
- Physical Sciences
- Chemistry
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