Magnetic manipulation of the reactivity of singlet oxygen: from test tubes to living cells

Abstract Although magnetism undoubtedly influences life on Earth, the science behind biological magnetic sensing is largely a mystery, and it has proved challenging, especially in the life sciences, to harness the interactions of magnetic fields (MFs) with matter to achieve specific ends. Using the well-established radical pair (RP) mechanism, we here demonstrate a bottom-up strategy for the exploitation of MF effects in living cells by translating knowledge from studies of RP reactions performed in vitro. We found an unprecedented MF-dependence of the reactivity of singlet oxygen (1O2) towards electron-rich substrates (S) such as anthracene, lipids, and iodide, in which [S•+ O2•−] RPs are formed as basis for MFs influencing molecular redox events in biological systems. The close similarity of the observed MF effects on the biologically relevant process of lipid peroxidation in solution, in membrane mimics, and in living cells shows that MFs can reliably be used to manipulate 1O2-induced cytotoxicity and cell apoptosis-related protein expression. These findings led to a ‘proof-of-concept’ study on MF-assisted photodynamic therapy in vivo, highlighting the potential of MFs as a non-invasive tool for controlling cellular events.