Advanced Instrumentation Institute, Korea Research Institute of Standards and Science (KRISS), Daejeon, 34113, Republic of Korea.
Department of Physics, Chungnam National University, Daejeon, 34134, Republic of Korea.
Sci Rep. 2020 Mar 17;10(1):4868. doi: 10.1038/s41598-020-61751-3.
Three-dimensional (3D) homo/heterogeneous DNA nanostructures were studied with low-voltage scanning transmission electron microscopy (LV-STEM). Four types of 3D DNA nanostructures were designed and fabricated by the origami method including newly proposed protocols. The low-energy electron probe and optimized dark-field STEM detector enabled individual unstained DNA nanostructures to be clearly imaged by the single acquisition without the averaging process. For the vertically stacked double structures, assembled through modified single-stranded domains, and the structures containing a square opening (i.e., a hole) in the center, the LV-STEM successfully reveals the vertical information of these 3D structures as the contrast differences compared to the reference. For the heterogeneous structures, the LV-STEM visualized both regions of the functionalized gold nanoparticles and the DNA base structure with distinct contrasts. This study introduces a straightforward method to fabricate stackable DNA nanostructures or nanoparticles by replacing a relatively small number of incumbent DNA strands, which could realize the simple and sophisticated fabrication of higher-order 3D DNA homo/hetero nanostructures. Together with these design techniques of DNA nanostructures, this study has demonstrated that the LV-STEM is the swift and simple method for visualizing the 3D DNA nanostructures and certifying the fabricated products as the specified design, which is applicable to various research fields on soft materials including DNA nanotechnology.
采用低电压扫描透射电子显微镜（LV-STEM）研究了三维（3D）同/异质 DNA 纳米结构。通过折纸法设计并制造了四种 3D DNA 纳米结构，包括新提出的方案。低能量电子探针和优化的暗场 STEM 探测器使单个未经染色的 DNA 纳米结构能够在单次采集过程中清晰成像，而无需进行平均处理。对于通过修饰的单链结构组装的垂直堆叠的双结构以及在中心具有正方形开口（即孔）的结构，LV-STEM 成功地揭示了这些 3D 结构的垂直信息，因为与参考相比存在对比度差异。对于异质结构，LV-STEM 以明显的对比度可视化了功能化金纳米粒子和 DNA 碱基结构的两个区域。本研究介绍了一种通过替换相对较少数量的现有 DNA 链来制造可堆叠 DNA 纳米结构或纳米粒子的简单方法，这可以实现更高级别 3D DNA 同/异质纳米结构的简单和复杂制造。结合这些 DNA 纳米结构的设计技术，本研究表明，LV-STEM 是一种快速简便的可视化 3D DNA 纳米结构的方法，并证明了所制造的产品符合指定设计，适用于包括 DNA 纳米技术在内的各种软物质研究领域。
