Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea.
Nanotechnology. 2017 Oct 6;28(40):405703. doi: 10.1088/1361-6528/aa871d. Epub 2017 Aug 18.
We report the fabrication and physical characteristics of niobium ion (Nb)-doped double-crossover DNA (DX-DNA) and salmon DNA (SDNA) thin films. Different concentrations of Nb ([Nb]) are coordinated into the DNA molecules, and the thin films are fabricated via substrate-assisted growth (DX-DNA) and drop-casting (SDNA) on oxygen plasma treated substrates. We conducted atomic force microscopy to estimate the optimum concentration of Nb ([Nb] = 0.08 mM) in Nb-doped DX-DNA thin films, up to which the DX-DNA lattices maintain their structures without deformation. X-ray photoelectron spectroscopy (XPS) was performed to probe the chemical nature of the intercalated Nb in the SDNA thin films. The change in peak intensities and the shift in binding energy were witnessed in XPS spectra to explicate the binding and charge transfer mechanisms between Nb and SDNA molecules. UV-visible, Raman, and photoluminescence (PL) spectra were measured to determine the optical properties and thus investigate the binding modes, Nb coordination sites in Nb-doped SDNA thin films, and energy transfer mechanisms, respectively. As [Nb] increases, the absorbance peak intensities monotonically increase until ∼[Nb] and then decrease. However, from the Raman measurements, the peak intensities gradually decrease with an increase in [Nb] to reveal the binding mechanism and binding sites of metal ions in the SDNA molecules. From the PL, we observe the emission intensities to reduce them at up to ∼[Nb] and then increase after that, expecting the energy transfer between the Nb and SDNA molecules. The current-voltage measurement shows a significant increase in the current observed as [Nb] increases in the SDNA thin films when compared to that of pristine SDNA thin films. Finally, we investigate the temperature dependent magnetization in which the Nb-doped SDNA thin films reveal weak ferromagnetism due to the existence of tiny magnetic dipoles in the Nb-doped SDNA complex.
我们报告了铌离子（Nb）掺杂双交叉 DNA（DX-DNA）和鲑鱼 DNA（SDNA）薄膜的制造和物理特性。不同浓度的 Nb（[Nb]）与 DNA 分子配位，通过基底辅助生长（DX-DNA）和滴铸（SDNA）在氧等离子体处理的基底上制备薄膜。我们进行原子力显微镜测量以确定 Nb 掺杂 DX-DNA 薄膜中 Nb 的最佳浓度（[Nb]=0.08mM），在该浓度下，DX-DNA 晶格保持其结构不变形。X 射线光电子能谱（XPS）用于探测 SDNA 薄膜中嵌入的 Nb 的化学性质。XPS 谱中见证了峰强度的变化和结合能的位移，以阐明 Nb 和 SDNA 分子之间的结合和电荷转移机制。紫外可见、拉曼和光致发光（PL）光谱用于确定光学性质，从而分别研究结合模式、Nb 在 Nb 掺杂 SDNA 薄膜中的配位位点和能量转移机制。随着[Nb]的增加，吸收峰强度单调增加，直到约[Nb]，然后减小。然而，从拉曼测量来看，随着[Nb]的增加，峰强度逐渐减小，揭示了金属离子在 SDNA 分子中的结合机制和结合位点。从 PL 中，我们观察到发射强度在达到约[Nb]之前减小，然后在那之后增加，期望 Nb 和 SDNA 分子之间的能量转移。与原始 SDNA 薄膜相比，电流-电压测量显示出随着 SDNA 薄膜中[Nb]的增加，电流显著增加。最后，我们研究了温度依赖的磁化，其中 Nb 掺杂的 SDNA 薄膜由于 Nb 掺杂的 SDNA 复合物中存在微小的磁偶极子而呈现弱铁磁性。
