Anomalous doping effect on Ag-doped DNA conductor

We report novel experimental results of chemical doping effect on Ag-doped DNA conductor. The prepared Ag-doped DNA samples were confirmed by EXAFS that Ag+ was doped into π-way. In I–V measurements at room temperature, nonlinear I–V curves with hysteresis emerged and systematic change in electrical conductivity σ was observed from 10−10 to 10−6 Ω−1 cm−1 under doping condition [Ag+]/[Base pair] = 10−6−10. The relation between the conductivity and dopant concentration showed a weak dependence σ ∝ [Ag+]0.5. This ‘weakly doping effect’ may be caused by the long-range correlated randomness of sequence in DNA, in contrast with usual doped organic conductors.