Bera Subhas C, Sanyal Kasturi, Senapati Dulal, Mishra Padmaja P
Chemical Sciences Division, Saha Institute of Nuclear Physics , Kolkata, India.
J Phys Chem B. 2016 May 12;120(18):4213-20. doi: 10.1021/acs.jpcb.6b01323. Epub 2016 Apr 29.
The complete unzipping of DNA double helix by small size gold nanoparticles having weakly positive surface charge has been monitored using ensemble and single molecule fluorescence resonance energy transfer (smFRET) techniques. We believe, as the gold nanoparticles have positive charge on the surface, the DNA and nanoparticles were pulled together to form two single strands. The positively charged ligands on the nanoparticles attached to the DNA, and the hydrophobic ligands of the nanoparticles became tangled with each other, pulling the nanoparticles into clusters. At the same time, the nanoparticles pulled the DNA apart. The conformational changes followed by unzipping have been investigated for long DNA (calf thymus DNA) as well as for short DNA (∼40 base pair) using ensemble methods like circular dichroism (CD) spectroscopy, fluorescence intercalation assay, viscometric method, and single molecule FRET imaging. This observation not only reveals a new aspect in the field of nano-bio interface but also provides additional information about DNA dynamics.
通过使用系综和单分子荧光共振能量转移（smFRET）技术，监测了具有弱正表面电荷的小尺寸金纳米颗粒对DNA双螺旋的完全解链过程。我们认为，由于金纳米颗粒表面带正电荷，DNA和纳米颗粒被拉到一起形成两条单链。纳米颗粒上带正电荷的配体与DNA结合，纳米颗粒的疏水配体相互缠结，将纳米颗粒拉成簇。与此同时，纳米颗粒将DNA拉开。使用诸如圆二色性（CD）光谱、荧光嵌入测定、粘度测定法和单分子FRET成像等系综方法，对长DNA（小牛胸腺DNA）以及短DNA（约40个碱基对）解链后的构象变化进行了研究。这一观察结果不仅揭示了纳米-生物界面领域的一个新方面，还提供了有关DNA动力学的更多信息。
