  Exaggerate radical-induced DNA damage under magnetic fields is of great
concerns to medical biosafety and to bio-molecular device based upon DNA
electronic conductivity. In this report, the effect of applying an external
magnetic field (MF) on DNA-mediated charge transport (CT) was investigated by
studying guanine oxidation by a kinetics trap (8CPG) via photoirradiation of
anthraquinone (AQ) in the presence of an external MF. Positive enhancement in
CT efficiencies was observed in both the proximal and distal 8CPG after
applying a static MF of 300 mT. MF assisted CT has shown sensitivities to
magnetic field strength, duplex structures, and the integrity of base pair
stacking. MF effects on spin evolution of charge injection upon AQ irradiation
and alignment of base pairs to CT-active conformation during radical
propagation were proposed to be the two major factors that MF attributed to
facilitate DNA-mediated CT. Herein, our results suggested that the electronic
conductivity of duplex DNA can be enhanced by applying an external MF. MF
effects on DNA-mediated CT may offer a new avenue for designing DNA-based
electronic device, and unraveled MF effects on redox and radical relevant
biological processes.
