Lin Lingling, Zhang Yan, Feng Zengfang, Li Na, Han Nannan, Zhou Jianzhang, Lin Zhonghua
State Key Laboratory of Physical Chemistry of the Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
J Nanosci Nanotechnol. 2011 Jun;11(6):4724-32. doi: 10.1166/jnn.2011.3855.
The pH-dependent conformational change of Calf thymus DNA (ctDNA, a typical giant DNA) binding with Fe3+ (Fe(3+)-ctDNA) for control of aggregation of gold nanoparticles (AuNPs) hybridized with Fe(3+)-ctDNA was described, which was attributed to the interaction between ctDNA and Fe3+. In acidic conditions, significant conformational change of ctDNA from elongated coil state to folded compact state occurs by binding of Fe3+ with the phosphate groups of ctDNA. The SPR absorbance and thus the colors of AuNPs hybridized with Fe(3+)-ctDNA would vary pH-dependently within the pH range 6.0-10.6 as the folded compact ctDNA could not stabilize AuNPs as effectively as the elongated coil ctDNA. Zeta potentials and Raman spectra were studied for revealing the interaction between Fe3+ and ctDNA as well as that between AuNPs and DNA (ctDNA and Fe(3+)-ctDNA). The conformational change of ctDNA driven by Fe3+ was also investigated using CD spectroscopy. This study prompts the possibility that the spectral, and thus color, change of AuNPs can be used to follow the conformational change of giant DNA driven by metal ions and biological relevant pH conditions.
描述了小牛胸腺DNA（ctDNA，一种典型的巨型DNA）与Fe3+（Fe(3+)-ctDNA）结合时pH依赖性的构象变化，以控制与Fe(3+)-ctDNA杂交的金纳米颗粒（AuNPs）的聚集，这归因于ctDNA与Fe3+之间的相互作用。在酸性条件下，通过Fe3+与ctDNA的磷酸基团结合，ctDNA会发生显著的构象变化，从细长的线圈状态转变为折叠的紧凑状态。由于折叠的紧凑ctDNA不能像细长的线圈ctDNA那样有效地稳定AuNPs，与Fe(3+)-ctDNA杂交的AuNPs的SPR吸光度以及颜色会在pH值6.0 - 10.6范围内随pH值变化。研究了zeta电位和拉曼光谱，以揭示Fe3+与ctDNA之间以及AuNPs与DNA（ctDNA和Fe(3+)-ctDNA）之间的相互作用。还使用圆二色光谱研究了由Fe3+驱动的ctDNA的构象变化。这项研究提示了这样一种可能性，即AuNPs的光谱变化以及由此产生的颜色变化可用于追踪由金属离子和生物相关pH条件驱动的巨型DNA的构象变化。
