Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States.
Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States.
ACS Nano. 2017 Oct 24;11(10):10529-10538. doi: 10.1021/acsnano.7b05902. Epub 2017 Oct 5.
Controlled three-dimensional positioning of nanoparticles is achieved by delivering single fluorescent nanoparticles from a nanopipette and capturing them at well-defined regions of an electrified substrate. To control the position of single nanoparticles, the force of the pressure-driven flow from the pipette is balanced by the attractive electrostatic force at the substrate, providing a strategy by which nanoparticle trajectories can be manipulated in real time. To visualize nanoparticle motion, a resistive-pulse electrochemical setup is coupled with an optical microscope, and nanoparticle trajectories are tracked in three dimensions using super-resolution fluorescence imaging to obtain positional information with precision in the tens of nanometers. As the particles approach the substrate, the diffusion kinetics are analyzed and reveal either subdiffusive (hindered) or superdiffusive (directed) motion depending on the electric field at the substrate and the pressure-driven flow from the pipette. By balancing the effects of the forces exerted on the particle by the pressure and electric fields, controlled, real-time manipulation of single nanoparticle trajectories is achieved. The developed approach has implications for a variety of applications such as surface patterning and drug delivery using colloidal nanoparticles.
通过从纳米管中输送单个荧光纳米粒子，并将其捕获在带电基底的明确定义区域，实现了纳米粒子的受控三维定位。为了控制单个纳米粒子的位置，通过平衡来自纳米管的压力驱动流的力与基底的吸引力静电场，提供了一种可以实时操纵纳米粒子轨迹的策略。为了可视化纳米粒子的运动，将电阻脉冲电化学装置与光学显微镜耦合，并使用超分辨率荧光成像在三维空间中跟踪纳米粒子轨迹，以获得具有数十纳米精度的位置信息。当粒子接近基底时，分析扩散动力学，根据基底的电场和来自纳米管的压力驱动流，揭示出亚扩散（受阻）或超扩散（定向）运动。通过平衡压力和电场对粒子施加的力的影响，实现了对单个纳米粒子轨迹的受控、实时操纵。所开发的方法对于各种应用具有重要意义，例如使用胶体纳米粒子进行表面图案化和药物输送。
