Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Centre, College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China.
Centre of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, Tianjin, People's Republic of China.
Nat Protoc. 2023 Jun;18(6):1958-1978. doi: 10.1038/s41596-023-00822-x. Epub 2023 Apr 12.
The ability to measure the behavior of a single molecule during a reaction implies the detection of inherent dynamic and static disordered states, which may not be represented when measuring ensemble averages. Here, we describe the building of devices with graphene-molecule-graphene single-molecule junctions integrated into an electrical circuit. These devices are simple to build and are stable, showing tolerance to mechanical changes, solution environment and voltage stimulation. The design of a conductive channel based on a single molecule enables single-molecule detection and is sensitive to variations in physical properties and chemical structures of the detected molecules. The on-chip setup of single-molecule junctions further offers complementary metal-oxide-semiconductor (CMOS) compatibility, enabling logic functions in circuit elements, as well as deciphering of reaction intermediates. We detail the experimental procedure to prepare graphene transistor arrays as a basis for single-molecule junctions and the preparation of nanogapped carboxyl-terminal graphene electrodes by using electron-beam lithography and oxygen plasma etching. We describe the basic design of a molecular bridge with desired functions and terminals to form covalent bonds with electrode arrays, via a chemical reaction, to construct stably integrated single-molecule devices with a yield of 30-50% per chip. The immobilization of the single molecules is then characterized by using inelastic electron tunneling spectra, single-molecule imaging and fluorescent spectra. The whole protocol can be implemented within 2 weeks and requires users trained in using ultra-clean laboratory facilities and the aforementioned instrumentation.
在反应中测量单个分子的行为的能力意味着检测固有动态和静态无序状态，而在测量整体平均值时可能无法表示这些状态。在这里，我们描述了将石墨烯-分子-石墨烯单分子结集成到电路中的器件的构建。这些器件易于构建且稳定，对机械变化、溶液环境和电压刺激具有耐受性。基于单个分子的导电通道的设计能够实现单分子检测，并且对所检测分子的物理性质和化学结构的变化敏感。单分子结的片上设置进一步提供互补金属氧化物半导体 (CMOS) 兼容性，能够在电路元件中实现逻辑功能，并对反应中间体进行解码。我们详细介绍了制备石墨烯晶体管阵列的实验程序，作为单分子结的基础，以及使用电子束光刻和氧等离子体刻蚀制备纳米间隙羧基末端石墨烯电极的程序。我们描述了具有所需功能和端子的分子桥的基本设计，通过化学反应与电极阵列形成共价键，以构建具有 30-50%芯片产率的稳定集成单分子器件。然后通过非弹性电子隧道谱、单分子成像和荧光光谱来表征单分子的固定化。整个方案可以在 2 周内完成，并且需要经过培训的用户使用超净实验室设施和上述仪器进行操作。
