School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
Biotechnol J. 2013 Jan;8(1):110-6. doi: 10.1002/biot.201200155. Epub 2012 Oct 24.
The interaction between nanoparticles (NPs) and DNA is of significance for both application and implication research of NPs. In this study, a single-molecule imaging technique based on atomic force microscopy (AFM) was employed to probe the NP-DNA interactions with quantum dots (QDs) as model NPs. Reproducible high-quality images of single DNA molecules in air and in liquids were acquired on mica by optimizing sample preparation conditions. Furthermore, the binding of QDs to DNA was explored using AFM. The DNA concentration was found to be a key factor influencing AFM imaging quality. In air and liquids, the optimal DNA concentration for imaging DNA molecules was approximately 2.5 and 0.25 μg/mL, and that for imaging DNA binding with QDs was 0.5 and 0.25 μg/mL, respectively. In the presence of QDs, the DNA conformation was altered with the formation of DNA condensates. Finally, the fine conformation of QD-DNA binding sites was examined to analyze the binding mechanisms. This work will benefit investigations of NP-DNA interactions and the understanding of the structure of NP-DNA bioconjugates. See accompanying article by Wang DOI: 10.1002/biot.201200309.
纳米粒子（NPs）与 DNA 的相互作用对于 NPs 的应用和意义研究都很重要。在这项研究中，我们采用基于原子力显微镜（AFM）的单分子成像技术，以量子点（QDs）作为模型 NPs 来探测 NP-DNA 相互作用。通过优化样品制备条件，在云母上获得了高质量的单 DNA 分子在空气和液体中的可重复成像。此外，我们还利用 AFM 研究了 QD 与 DNA 的结合。发现 DNA 浓度是影响 AFM 成像质量的关键因素。在空气和液体中，用于成像 DNA 分子的最佳 DNA 浓度分别约为 2.5 和 0.25 μg/mL，用于成像与 QD 结合的 DNA 的最佳 DNA 浓度分别为 0.5 和 0.25 μg/mL。在 QD 存在下，DNA 构象发生变化，形成 DNA 凝聚物。最后，检查了 QD-DNA 结合位点的精细构象，以分析结合机制。这项工作将有助于研究 NP-DNA 相互作用，以及理解 NP-DNA 生物缀合物的结构。见 Wang 文章 DOI: 10.1002/biot.201200309。
