How the surrounding water changes the electronic and magnetic properties   of DNA
  Strong influence of water molecules on the transport and magnetic properties of DNA, observed in this study, opens up real opportunities for application of DNA in molecular electronics. Interaction of the nucleobases with water molecules leads to breaking of some of the $\pi$ bonds and appearance of unbound pi electrons. These unbound electrons contribute significantly to the charge transfer at room temperature by up to 1000 times, but at low temperature the efficiency of charge transfer is determined by the spin interaction of the two unbound electrons located on the intrastrand nucleobases. The charge exchange between the nucleobases is allowed only when the spins of unbound electrons are antiparallel. Therefore, the conductance of the DNA molecule can be controlled by a magnetic field. That effect has potential applications for developing a nanoscale spintronic device based on the DNA molecule, where efficiency of spin interaction will be determined by the DNA sequence. 
Julia Berashevich and Tapash Chakraborty