Liu Yang, Xu Cong, Gao Tienan, Chen Xuwei, Wang Jianhua, Yu Ping, Mao Lanqun
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
ACS Sens. 2020 Aug 28;5(8):2351-2358. doi: 10.1021/acssensors.9b02520. Epub 2020 Jul 28.
Developing new methods and techniques for the size analysis of particles in a solution is highly desirable not only for the industrial screening of particles but also for single biological entity analysis (., single cells or single vesicles). Herein, we report a new technique for sizing single particles in a solution with a nanopipette. The rationale is essentially based on ion-current blockage when the particles approach the proximity of a nanopipette orifice. By rationally controlling the geometry of the nanopipette and the applied potential, the spike-type ion current transient generated from the motion of particles in the process of "collision and departure" is employed for sizing single particles. The results show that both the relative ion-current change (Δ/) and the dwell time (Δ) of spike-type transient are dependent on particle size. Differently, Δ is also related to an externally applied voltage. Statistical analysis shows that Δ/ is proportional to the particle diameter, and this linear relationship is further understood by finite-element simulations. This study not only provides a new principle for sizing single particles in a solution but also is helpful to understand the motion of a particle near the orifice of the nanopipette.
开发用于溶液中颗粒尺寸分析的新方法和技术非常必要，这不仅适用于颗粒的工业筛选，也适用于单个生物实体分析（如单细胞或单囊泡）。在此，我们报告了一种使用纳米吸管对溶液中的单个颗粒进行尺寸测量的新技术。其原理本质上基于颗粒接近纳米吸管孔口时的离子电流阻塞。通过合理控制纳米吸管的几何形状和施加的电势，利用“碰撞和离开”过程中颗粒运动产生的尖峰型离子电流瞬变来测量单个颗粒的尺寸。结果表明，尖峰型瞬变的相对离子电流变化（Δ/）和停留时间（Δ）均取决于颗粒大小。不同的是，Δ还与外部施加的电压有关。统计分析表明，Δ/与颗粒直径成正比，通过有限元模拟进一步理解了这种线性关系。本研究不仅为溶液中单个颗粒的尺寸测量提供了新原理，也有助于理解颗粒在纳米吸管孔口附近的运动。
