Centre for Personalized Nanomedicine, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Corner of College and Cooper Roads (Building 75), Brisbane, Queensland 4072, Australia.
Langmuir. 2021 Apr 27;37(16):4772-4782. doi: 10.1021/acs.langmuir.0c03083. Epub 2021 Apr 19.
Recent advances in solid-state and biological nanopore sensors have produced a deluge of analytical techniques for in situ characterization of bio-nano colloidal dispersions; however, the transport forces governing particle movement into and out of the nanopore are not yet fully understood. Herein, we study the motion of particles outside the smaller opening of an elastomeric size-tunable nanopore and relate this motion to existing transport forces known to act on particles within the pore. Subsequently, we develop a combined optoelectronic approach which allows the comparison of both resistive pulse sensing and single particle tracking-based techniques for particle size characterization and, intriguingly, measurements of the ensemble particle motion induced by a combination of particle electrophoresis as well as pressure-driven and electroosmotic flows through the sensor nanopore. We find evidence suggesting that although bulk fluid flow from the pore tends to drive particle motion, in certain circumstances, electrophoretically driven motion can dominate bulk fluid flow-driven motion even at large distances from the pore opening. By permitting direct observation of the behavior of fluids at the nanopore interface, this approach enables a greater understanding of the transport forces acting on particles as they migrate toward and move through nanopore sensors-with implications for future particle characterization systems and for nanopore methods in general.
近年来，固态和生物纳米孔传感器的发展带来了大量用于原位生物纳米胶体分散体特性分析的技术；然而，控制颗粒进出纳米孔的输运力尚未完全理解。在此，我们研究了弹性体尺寸可调纳米孔较小开口外的颗粒运动，并将这种运动与已知作用于孔内颗粒的现有输运力联系起来。随后，我们开发了一种组合光电方法，允许对基于电阻脉冲感应和单颗粒跟踪的技术进行比较，用于颗粒尺寸表征，并且有趣的是，还可以测量由颗粒电泳以及通过传感器纳米孔的压力驱动和电动流组合引起的整体颗粒运动。我们有证据表明，尽管来自孔的体相流体流动倾向于驱动颗粒运动，但在某些情况下，电泳驱动的运动甚至可以在远离孔开口的较大距离处主导体相流体流动驱动的运动。通过允许直接观察纳米孔界面处的流体行为，这种方法可以更好地了解颗粒在向纳米孔传感器迁移并穿过传感器时所受的输运力，这对未来的颗粒特性分析系统和纳米孔方法都具有重要意义。
