The volume of the object that can be manipulated in solution is continuously decreasing toward an ultimate goal of a single molecule. However, Brownian motions suppress the molecular trapping. To date, free-molecule trapping in solution has not been accomplished. Here, we develop a strategy to directly trap, investigate, and release single molecules (∼2 nm) in solution by using an adjustable plasmonic optical nanogap, which has been further applied for selective single-molecule trapping. Comprehensive experiments and theoretical simulations demonstrated that the trapping force originated from plasmonic nanomaterials. This technique opens an avenue to manipulate single molecules and other objects in the size range of primary interest for physics, chemistry, and life and material sciences without the limitations of strong bonding group, ultra-high vacuum, and ultra-low temperature, and makes possible controllable single-molecule manipulation and investigation as well as bottom-up construction of nanodevices and molecular machines.

可以在溶液中操作的物体的体积朝着单个分子的最终目标不断减小。但是，布朗运动抑制了分子​​陷阱。迄今为止，溶液中的自由分子捕获尚未完成。在这里，我们开发了一种通过使用可调节的等离激元光学纳米间隙直接捕获，研究和释放溶液中的单分子（〜2 nm）的策略，该策略已进一步应用于选择性单分子捕获。综合实验和理论模拟表明，俘获力源自等离子体纳米材料。这项技术为在物理，化学，生命和材料科学领域关注的主要范围内的单个分子和其他物体开辟了一条途径，而不受强键合基团的限制，