Phase, current, absorbance, and photoluminescence of double and triple metal ion-doped synthetic and salmon DNA thin films.

We fabricated synthetic double-crossover (DX) DNA lattices and natural salmon DNA (SDNA) thin films, doped with 3 combinations of double divalent metal ions (M2+ )-doped groups (Co2+ -Ni2+ , Cu2+ -Co2+ , and Cu2+ -Ni2+ ) and single combination of a triple M2+ -doped group (Cu2+ -Ni2+ -Co2+ ) at various concentrations of M2+ ([M2+ ]). We evaluated the optimum concentration of M2+ ([M2+ ]O ) (the phase of M2+ -doped DX DNA lattices changed from crystalline (up to ([M2+ ]O ) to amorphous (above [M2+ ]O )) and measured the current, absorbance, and photoluminescent characteristics of multiple M2+ -doped SDNA thin films. Phase transitions (visualized in phase diagrams theoretically as well as experimentally) from crystalline to amorphous for double (Co2+ -Ni2+ , Cu2+ -Co2+ , and Cu2+ -Ni2+ ) and triple (Cu2+ -Ni2+ -Co2+ ) dopings occurred between 0.8 mM and 1.0 mM of Ni2+ at a fixed 0.5 mM of Co2+ , between 0.6 mM and 0.8 mM of Co2+ at a fixed 3.0 mM of Cu2+ , between 0.6 mM and 0.8 mM of Ni2+ at a fixed 3.0 mM of Cu2+ , and between 0.6 mM and 0.8 mM of Co2+ at fixed 2.0 mM of Cu2+ and 0.8 mM of Ni2+ , respectively. The overall behavior of the current and photoluminescence showed increments as increasing [M2+ ] up to [M2+ ]O , then decrements with further increasing [M2+ ]. On the other hand, absorbance at 260 nm showed the opposite behavior. Multiple M2+ -doped DNA thin films can be used in specific devices and sensors with enhanced optoelectric characteristics and tunable multi-functionalities.