中文摘要：

在碱性环境下,向DNA溶液中加入较低浓度的镍离子制备了金属DNA（M-DNA）,并分别对单根DNA和M-DNA的导电性进行了测量.结果表明,二者均表现出半导体性质;随镍离子浓度的增加导电性明显增强,伏特间隙减小;当镍离子浓度超过0.1 mmol/L时,DNA的电导几乎不随镍离子浓度变化.在中性环境下向DNA溶液中加入较高浓度的镍离子,实现了DNA从右手到左手螺旋结构的转变.利用STM观察到了左手螺旋结构的Z-DNA,Z构象可以分辨出大沟与小沟,并且螺旋结构不均匀,伴有局部的解旋和无序化;单根Z-DNA的导电性明显减弱.DNA,M-DNA,Z-DNA的电导大小关系为GM-DNA〉GDNA〉GZ-DNA.通过紫外吸收和Raman光谱测量发现,使DNA发生右手到左手螺旋结构转变的镍离子浓度约为1.7 mol/L.

英文摘要：

The modified M-DNA molecular wires were prepared by adding nickel ions of low concentration to the calf thymus DNA in alkaline solution.And we investigated the conductivity of single DNA and M-DNA molecules.The results indicated that the M-DNA and the B-DNA show semiconductor properties.But the conductivity of M-DNA is higher than that of the B-DNA,and the voltage gap is smaller.When the concentration of nickel ions is more than 0.1 m mol/L,the conductance of DNA does not change with the nickel concentration.In addition,the right to lefthanded DNA transition was realized by adding nickel ions of appropriate concentration to the calf thymus DNA in neutral solution and the structure of left handed Z-DNA was observed by STM.The result showed that the major and minor grooves are obvious,unwinding and disordering regions can be found in the Z-DNA.The conductivity of left-handed DNA was much lower than that of the B-DNA.The conductivity relationship of B-DNA,M-DNA and Z-DNA is GM-DNA〉GB-DNA〉GZ-DNA.The UV absorption spectra and the Raman spectra indicated that the transition of B-Z DNA appears when the concentration of nickel ions is about 1.7 mol/L.