Electronic states and magnetism of doped DNA

近年来，人们对DNA的物理性质进行了各种各样的研究。也就是说，这些引人注目的争论已经聚集了对DNA内在本质的强烈科学兴趣。该项目的目的是揭示DNA的内在物理性质，并研究DNA在纳米线上的潜在适用性，这可能在不久的将来支持电子产品的进一步工业发展。为了避免在DNA调查中提出的问题，我们计划利用磁手段，如ESR和SQUID磁力计。(1)天然DNA的内在物理性质我们已经开始研究从睾丸中提取的鲑鱼DNA，并进行了两种不同级别的纯化：一种是粗鲑鱼DNA粉，另一种是细鲑鱼DNA纤维。三文鱼DNA粉的ESR光谱强度相对较强，约为每碱基对（bp）的0.2%。然而，我们在小于50 ppm/bp的三文鱼DNA纤维中获得了极弱的ESR信号，这可能是由于三文鱼DNA纤维中杂质的影响。这一发现表明，有关Re-metal电极超导性的类金属行为甚至激发邻近效应的报道应该重新考虑。因此，我们得出结论，天然鲑鱼DNA是具有大带隙的半导体，正如最近报道的光学吸收数据中具有超过4 eV的带间吸收能量。(2)二价金属离子掺杂脱氧核糖核酸的物理性质近年来也引起了人们的广泛关注，因为它在纳米电子学领域具有作为纳米线的潜在应用前景。DNA具有很高的碱基排列设计灵活性和良好的自组织能力。目前已有八面体纳米结构的报道。然而，如上所述，天然DNA是一种半导体。然后，我们必须将载流子引入天然DNA中。在这里，我们采用了在碱基对的碱基之间掺杂二价金属离子的方法。我们用M=Ca, Mg, Zn, Cu, Mn, Co， Ni等多种金属离子制备M- dna，并测量了ESR和SQUID的敏感性。由于结果表明几乎所有的金属离子都是保持二价掺杂的，所以我们不能确定载流子掺杂到基π带。然而，三维金属离子为研究磁相互作用提供了有趣的模板。此外，我们发现在Fe- dna中发生了从Fe到碱π带的净电荷转移。另一方面，在Mn-DNA中，我们发现从b型到a型的相变发生在天然DNA中。在a型Mn-DNA中，我们证实了af样磁相变的存在。我们希望进一步揭示纳米电子学潜在应用的可能性。少

In recent years, variety of investigations has been reported on the physical nature of DNA. That is, the striking controversies have gathered the strong scientific interest on the intrinsic nature of DNA. The aim of this project is to unveil the intrinsic physical properties of DNA and research the potential applicability of DNA to nanowires which might support further industrial developments of electronics in the near future. To avoid the suggested issues in the DNA investigations, we have planed to utilize the magnetic means such as ESR and SQUID magnetometer.(1) Intrinsic physical properties of natural DNAWe have started our project to study the salmon DNA extracted from a testis with two different grades of purification: one is the crude salmon DNA powder and the other is the fine salmon DNA fiber. The ESR spectra in the salmon DNA powder have a relatively strong intensity, approximately 0.2 % per base pair (bp) of DNA. However, we obtained the extremely weak ESR signal from the sa … More lmon DNA fiber less than 50 ppm/bp, which could be ascribed to the effect of impurities in the salmon DNA fiber. This finding suggests that the reports with the metallic-like behavior or even exciting proximity effect of the superconductivity of the Re-metal electrodes should be reconsidered. Thus, we concluded that the natural salmon DNA is a semiconductor with a large band gap, as in the recently reported optical absorption data with more than 4 eV of the inter-band absorption energy.(2) Physical properties of divalent metal ion doped DNADNA also attracts a lot of interest in these years because of the potential application to the nanoelectronics as nanowires. DNA shows high flexibility in design of base arrangements and excellent ability of self-organization. The nano architecture with octahedral structure has been reported so far. However, as revealed in the above, the natural DNA is a semiconductor. Then, we have to introduce the charge carriers into the natural DNA.Here, we applied the doping method with the divalent metal ions in between the bases of a base pair. We prepared M-DNA with a variety of metal ions, such as M=Ca, Mg, Zn, Cu, Mn, Co, Ni, etc. and measured both of ESR and SQUID susceptibility. Since the result suggests that almost of the metal ions are doped keeping the valence two, we cannot establish the charge carrier doping into the base π-band. However, 3d metal ions provided the interesting templates for studying the magnetic interactions. Furthermore, we found that in Fe-DNA the net charge transfer from Fe to the base π-band has occurred. On the other hand, in Mn-DNA, we discovered that the phase transition from the B-form to the A-form takes place as in the natural DNA. In the A-form Mn-DNA, we confirmed the presence of AF-like magnetic phase transition. We would like to proceed further to unveil the possibility of potential application to nano-electronics. Less