Ussembayev Yera, Beunis Filip, Oorlynck Lucas, Bahrami Mohammadreza, Strubbe Filip, Neyts Kristiaan
LCP Research Group, Ghent University, Technologiepark 126, 9052 Gent, Belgium.
Center for Nano- and Biophotonics, Ghent University, Technologiepark 126, 9052 Gent, Belgium.
ACS Nano. 2023 Nov 28;17(22):22952-22959. doi: 10.1021/acsnano.3c08161. Epub 2023 Oct 3.
100 years ago, in 1923, the Nobel prize in physics was awarded for measurement of the unit charge. In addition to a profound impact on contemporary physics, this discovery has reshaped our understanding of charge-based interactions in chemistry and biology, ranging from oxidation and ionization to protein folding and metabolism. In a liquid, the discrete nature of the electric charge becomes prominent at the nanoscale when a charge carrier is exchanged between a molecule or a nanoparticle and the surrounding medium. However, our ability to observe the dynamics of such interactions at the level of a single elementary charge is limited due to the abundance of ions in water. Here, we report on the observation of single binding-unbinding events with elementary charge resolution at the surface of a nanoparticle suspended in water. Discrete steps in the electrical charge are revealed by analyzing the motion of optically trapped nanoparticles under the influence of an applied sinusoidal electric field. The measurements are sufficiently fast and long to observe individual (dis)charging events that occur on average every 3 s. Our results offer prospective routes for studying the dynamics of diverse chemical and biological phenomena on the nanoscale with elementary charge resolution.
100年前，即1923年，诺贝尔物理学奖授予了单位电荷测量领域。这一发现不仅对当代物理学产生了深远影响，还重塑了我们对化学和生物学中基于电荷相互作用的理解，涵盖从氧化、电离到蛋白质折叠和新陈代谢等诸多方面。在液体中，当电荷载体在分子或纳米颗粒与周围介质之间交换时，电荷的离散性质在纳米尺度上变得显著。然而，由于水中离子的大量存在，我们在单个基本电荷层面观察此类相互作用动力学的能力受到限制。在此，我们报告了在悬浮于水中的纳米颗粒表面以基本电荷分辨率观察单个结合-解离事件的情况。通过分析在施加的正弦电场影响下光学捕获的纳米颗粒的运动，揭示了电荷的离散步骤。这些测量足够快速且持久，能够观察到平均每3秒发生一次的单个（去）充电事件。我们的结果为以基本电荷分辨率研究纳米尺度上各种化学和生物现象的动力学提供了潜在途径。
